| 田中 敬二（たなか けいじ） | データ更新日：2024.02.12 |
教授 ／
工学研究院
応用化学部門
機能物質化学
| 1. | D. Kawaguchi, K. Sasahara, M. Inutsuka, T. Abe, S. Yamamoto, K. Tanaka,, Absolute Local Conformation of Poly(Methyl Methacrylate) Chains Adsorbed on a Quartz Surface, J. Chem. Phys., 10.1063/5.0184315, 159, 24, 244902, 2023.12, Polymer chains at a buried interface with an inorganic solid play a critical role in the performance of polymer nanocomposites and adhesives. Sum frequency generation (SFG) vibrational spectroscopy with a sub-nanometer depth resolution provides valuable information regarding the orientation angle of functional groups at interfaces. However, in the case of conventional SFG, since the signal intensity is proportional to the square of the second-order nonlinear optical susceptibility and thereby loses phase information, it cannot be unambiguously determined whether the functional groups face upward or downward. This problem can be solved by phase-sensitive SFG (ps-SFG). We here applied ps-SFG to poly(methyl methacrylate) (PMMA) chains in direct contact with a quartz surface, shedding light on the local conformation of chains adsorbed onto the solid surface. The measurements made it possible to determine the absolute orientation of the ester methyl groups of PMMA, which were oriented toward the quartz interface. Combining ps-SFG with all-atomistic molecular dynamics simulation, the distribution of the local conformation and the driving force are also discussed..  |
| 2. | S. Hamamoto, M. Oura, A. Shundo, D. Kawaguchi, S. Yamamoto, H. Takano, M. Uesugi, A. Takeuchi, T. Iwai, Y. Seto, Y. Joti, K. Sato, K. Tanaka, T. Hatsui,, Demonstration of Efficient Transfer Learning in Segmentation Problem in Synchrotron Radiation X-ray CT Data for Epoxy Resin, Sci. Technol. Adv. Mater. Meth., 10.1080/27660400.2023.2270529, 3, 1, 2270529, 2023.11, Synchrotron radiation X-ray computed tomography (CT) provides information about the three-dimensional electron density inside a sample with a high spatial resolution. Recently, the need to examine the internal structure of materials composed of light elements, such as water and carbon fibers in resins, has increased. Small density differences in these systems give low X-ray contrast; segmentation methods suited for this type of problem are necessary. Machine learning is typically used to analyze CT data, and a large amount of training data is required to train a machine learning model. Conversely, transfer learning, which uses existing learning models, can develop a learning model using only a small amount of training data. In this study, the synchrotron radiation X-ray CT images of an epoxy resin containing water have been analyzed using transfer learning as the validation of a method for analyzing low-contrast CT data with high accuracy. Circular domain structures in the resin have been observed using the X-ray CT method, and statistical information about these structures has been successfully obtained by transfer learning-based analysis. Here, transfer learning is performed using twelve slices within an X-ray CT 3D image, demonstrating that low-contrast synchrotron CT data can be segmented with a small amount of training data.. |
| 3. | H. Matsuno, R. Eto, M. Fujii, M. Totani, K. Tanaka, Effect of Segmental Motion on Hydrolytic Degradation of Polyglycolide in Electro-Spun Fiber Mats, Soft Matter, doi.org/10.1039/D3SM00613A, 19, 38, 7459-7467, 2023.09, Recently, environmentally degradable polymers have received great attention from the perspective of sustaining the aquatic environment. To control the degradation behavior of solid polymer materials in an aqueous phase, it is crucial to better understand the thermal molecular motion of polymer chains in water. We herein focus on polyglycolide (PGA), which is one of the representative aliphatic polyesters that are hydrolytically degradable. Three kinds of fiber mats of PGA with different fiber diameters and comparable crystallinities were prepared using an electrospinning method. Our choice of fiber mats was because the ratio of the surface area, where the hydrolytic degradation starts to occur, to the volume was larger than that for the films. Dynamic mechanical analysis (DMA) enabled us to gain direct access to the dynamic glass transition temperature (Tgα) of PGA in the fiber mats both in dry gaseous nitrogen and liquid water. The Tgα value varied not only with the presence of water molecules, but also with the fiber diameter, or the specific surface area. The degradation behavior of PGA fiber mats was examined by immersing the samples in phosphate-buffered saline at various temperatures. When the segmental motion of PGA in the fiber mats was released, the apparent crystallinity of the mats increased, meaning that PGA amorphous chains were cleaved and thus partially eluted into the aqueous phase. It was also shown that partially cleaved chains crystallized.. |
| 4. | R. Eto, H. Mokudai, T. Masaki, H. Matsuno, K. Tanaka, Hydrolysis Properties of Polyglycolide Fiber Mats Mixed with a 3 Hyperbranched Polymer as a Degradation Promoter, Polym. J., doi.org/10.1038/s41428-023-00828-y, 56, 55-60, 2023.09, In response to the problem of microplastics, polyesters are attracting great attention due to their degradability in underwater 9 environments. We recently demonstrated that the hydrolysis of linear polyglycolide (PGA) in a fiber state strongly depends 10 on segmental dynamics in aqueous phases. This finding implies that the degradation of PGA can be controlled by tuning the 11 segmental dynamics in water. Our choice of fiber geometry was based on its relatively large surface area-to-volume ratio. 12 Herein, we examined the effects of the addition of a hyperbranched polymer (HBP) with a polyester skeleton and with many 13 terminal hydroxy groups on the degradability characteristics of fiber mats. Dynamic mechanical analysis revealed that HBP 14 acted as a plasticizer, especially in underwater environments. The weight loss of the PGA fiber mats was accelerated with 15 increasing HBP content. In addition, structural analyses confirmed that crystal degradation had occurred and that hydrolysis- 16 cleaved chains had crystallized. Considering that the structural changes in the PGA crystals depended on the feed amount of 17 HBP, we claimed that HBP promoted PGA degradation in both the amorphous and crystalline phases. We believe that our 18 simple strategy for accelerating the degradation of polyesters can provide suggestions for solving issues with microplastics.. |
| 5. | K. Kawahara, H. Matsuno, K. Tanaka, Aggregation States and Segmental Dynamics of Poly(methyl methacrylate) in Nanofiber Mats, Langmuir, DOI: 10.1021/acs.langmuir.3c00698, 39, 20, 7192-7200, 2023.05, Nanofiber mats composed of polymers, having a large surface-to-volume ratio and high porosity, have been widely applied in the environmental and biomedical fields but fundamental knowledge on the polymer chains in the mats seems to be limited. We here report the aggregation states and segmental dynamics of poly(methyl methacrylate)s (PMMAs) with different stereoregularities in electrospun nanofiber mats. Attenuated total reflectance Fourier transform infrared (ATR/FTIR) spectroscopy revealed that, in the case of atactic PMMA (at-PMMA), the population of the trans–trans conformation of the main chain part, which allows carbonyl groups of the side group to interact affirmatively with each other, increased in the electrospun nanofiber mat. On the other hand, in the case of isotactic PMMA (it-PMMA), the skeletal conformation was unchanged even in the nanofiber mat. As a result of the aggregation states of PMMA chains, the glass-transition temperature (Tg) of the electrospun nanofiber mats increased and remained unchanged from the corresponding bulk value for at- and it-PMMA, respectively. These findings should be useful for designing materials and devices composed of electrospun nanofibers.. |
| 6. | S. Yamamoto, R. Ida, M. Aoki, R. Kuwahara, A. Shundo, K. Tanaka, Formation Mechanism of a Heterogeneous Network in Epoxy Resins, Macromolecules, 10.1021/acs.macromol.3c00411, 56, 11, 3913-3921, 2023.05, In general, the network structure formed in epoxy resins is heterogeneous, and its extent is dependent on the curing temperature. Based on Fourier-transform infrared spectroscopy in conjunction with coarse-grained molecular dynamics simulations, we herein discuss the origin of mesoscopic heterogeneity in an epoxy resin composed of a typical epoxy base and diamine hardener, which react with each other in two steps. The rate balance of the first and second step reactions, which led to chain extension and branching, respectively, depended on the curing temperature; at a higher temperature, the second-step reaction became faster. Since the reaction proceeded more slowly at lower temperatures, a homogeneous domain was formed as unreacted substances were incorporated into the network. At higher temperatures, on the other hand, the reaction proceeded rapidly before unreacted substances were incorporated into the network, leaving isolated small fragments and nanoscale voids or free spaces in the domain. We also found that an actively reacting domain with a length scale of several tens of nanometers was formed even at a conversion lower than the gel point, regardless of the curing temperature. The connection of domains was also key to better understanding the temperature dependence of the hierarchical heterogeneity. The final network was found to be denser and more homogeneous at a lower temperature, while heterogeneous with many free spaces at a higher temperature. Our molecular picture of the network formation drawn by combining experimental and simulation techniques advances our current understanding of the heterogeneity formed in epoxy resins.. |
| 7. | A. Shundo, M. Aoki, P. Wang, T. Hoshino, S. Yamamoto, S. Yamada, K. Tanaka, Effect of Heterogeneous Network on Fracture Behavior of Epoxy Resins, Macromolecules, 10.1021/acs.macromol.3c00341, 56, 11, 3884-3890, 2023.05. |
| 8. | K. Uchida, K. Mita, S. Yamamoto, K. Tanaka, Conformational Relaxation of Ethylene-Propylene-Diene Terpolymer at a Solid Interface, Polym. J., DOI:10.1038/s41428-023-00764-x, 55, 683-690, 2023.03, The relaxation of the local conformation of ethylene-propylene-diene terpolymer (EPDM) rubber at the quartz interface was examined by sum frequency generation (SFG) spectroscopy in conjunction with all-atom molecular dynamics (MD) simulations. At room temperature, SFG peaks due to the CH symmetric stretching vibration of methyl (CH3s) and methylene (CH2s) groups were observed, and the intensity was stronger for CH3s than for CH2s. The CH3s to CH2s intensity ratio was reversed during the heating process, meaning that the local conformation of EPDM at the interface changed. MD simulations revealed that the fraction of ethylene units in the trans conformation on the substrate surface decreased once the temperature was greater the interfacial glass transition temperature (Tg), which was determined based on the temperature dependence of the mass density. Moreover, the temperature-induced change in the fraction of propylene units in the trans conformation was less remarkable than that of ethylene units. Both SFG spectroscopy and MD simulation confirmed that the Tg was higher in the interfacial region than in the bulk.. |
| 9. | 甲加晃一, 日笠茂樹, 織田ゆか里, 川口大輔, 田中敬二, ポリプロピレン系複合材料の力学特性に及ぼす無水マレイン酸変性ポリプロピレンの酸価および体積分率の効果, 日本接着学会誌, 59, 1, 11-16, 2023.01. |
| 10. | D. Kawaguchi, R. Nakayama, H. Koga, M. Totani, K. Tanaka, Improvement of Polymer Adhesion by Designing the Interface Layer, Polymer, 10.1016/j.polymer.2022.125581, 265, 125581, 2023.01, Polymer adhesion with inorganic materials is a key technology for realizing the diversification of materials. When a polymer contacts with inorganic materials, a layer containing strongly- and loosely-adsorbed chains is formed at the surface. The former and latter are chains that adopt mainly train and loop/tail conformations, respectively. To improve the interfacial adhesion, it is of pivotal importance to control the interaction between loosely-adsorbed chains, which are in part directly attached to the solid surface, and bulk free chains. We here succeeded in increasing the interfacial strength by chemically cross-linking them. Polymer chains were attached to the surface of a silicon wafer and then a film of isotactic polypropylene or polyamide 6 was mounted on it to produce our model system. As loosely-adsorbed chains have photo-cross-linkable moieties, the polyolefin or engineering plastic film could be strongly adhered to the silicon wafer via the adsorbed layer. On the other hand, the film could be easily detached from the wafer having loosely-adsorbed chains without photo-cross-linkable groups. Our facile idea that loosely-adsorbed interfacial chains chemically bond to the polymer bulk shows promise for the design and construction of not only interfacial adhesion but also composite materials.. |
| 11. | X.-F. Shen, M. Watanabe, A. Takagaki, J. T. Song, T. Abe, D. Kawaguchi, K. Tanaka, T. Ishihara, Pyridyl Anchoring Squaraine as a Near-infrared Dye Sensitizer for Effective Sensitized Hydrogen Production over a Titanium Dioxide Photocatalyst in Water Medium, Applied Physics A, 10.1007/s00339-022-06281-7, 129, 1, 28, 2022.12. |
| 12. | Y. Morimitsu, H. Matsuno, Y. Oda, S. Yamamoto, K. Tanaka, Direct Visualization of Cooperative Adsorption of a String-like Molecule onto a Solid, Science Advances, 10.1126/sciadv.abn6349, 8, 41, 6349, 2022.10, Natural systems, composite materials, and thin-film devices adsorb macromolecules in different phases onto their surfaces. In general, polymer chains form interfacial layers where their aggregation states and thermal molecular motions differ from the bulk. Here, we visualize well-defined double-stranded DNAs (dsDNAs) using atomic force microscopy and molecular dynamics simulations to clarify the adsorption mechanism of polymer chains onto solid surfaces. Initially, short and long dsDNAs are individually and cooperatively adsorbed, respectively. Cooperative adsorption involves intertwining of multiple chains. The dependence of adsorption on the chain affects the formation of the interfacial layer, realizing different mechanical properties of DNA/filler bulk composites. These findings will contribute to the development of light and durable polymer composites and films for various industrial, biomedical, and environmental applications.. |
| 13. | D. Kawaguchi, A. Higasayama, Y. Ogata, T. Kabe, Y. Matsushita, K. Tanaka, Crystalline Structure, Molecular Motion and Photo-carrier Formation in Thin Films of Monodisperse Poly(3-hexylthiophene) with Various Molecular Weights, Polym. J., 10.1038/s41428-022-00713-0, 55, 497-505, 2022.10, A better understanding of the carrier formation process for semiconducting polymers, especially in thin films, is essential for designing and constructing highly functionalized polymeric optoelectronic devices. Here, the effects of aggregation states and thermal molecular motion on photocarrier formation in melt-crystallized thin films of monodispersed poly(3-hexylthiophene) (P3HT) are discussed. Grazing incidence X-ray diffraction measurements revealed that the crystalline ordering in the films was greatly influenced by the molecular weight (MW) of P3HT. In contrast, dynamic mechanical analysis (DMA) revealed that the MW had no significant effects on the α1 relaxation process, which corresponded to the twisting motion of thiophene rings in the crystalline phase unless the MW was quite small. Femtosecond transient absorption (TAS) spectroscopy showed that better crystalline ordering led to the direct formation of polarons (P) from hot excitons at room temperature. Once the temperature went beyond Tα1, at approximately 310 K, the P formation process from polaron pairs (PP) was activated. Thus, it can be claimed that the P formation for P3HT could be regulated by the thermal molecular motion in addition to the crystalline structure. The knowledge obtained here should be useful for a better molecular design of semiconducting polymers that can be applied to optoelectronic devices.. |
| 14. | K. Yamaguchi, D. Kawaguchi, N. Miyata, T. Miyazaki, H. Aoki, S. Yamamoto, K. Tanaka, Kinetics of the Interfacial Curing Reaction for an Epoxy–Amine Mixture, Physical Chemistry Chemical Physics, 10.1039/d2cp03394a, 24, 36, 21578-21582, 2022.09, A better understanding of the chemical reaction between epoxy and amine compounds at a solid interface is crucial for the design and fabrication of materials with appropriate adhesive strength. Here, we examined the curing reaction kinetics of epoxy phenol novolac and 4,4'-diaminodiphenyl sulfone at the outermost interface using sum-frequency generation spectroscopy, and X-ray and neutron reflectivity in conjunction with a full atomistic molecular dynamics simulation. The reaction rate constant was much larger at the quartz interface than in the bulk. While the apparent activation energy at the quartz interface obtained from an Arrhenius plot was almost identical to the bulk value, the frequency factor at the quartz interface was greater than that in the bulk. These results could be explained in terms of the densification and orientation of reactants at the interface, facilitating the encounter of the reactants present.. |
| 15. | H. Ogawa, M. Aoki, S. Ono, Y. Watanabe, S. Yamamoto, K. Tanaka, M. Takenaka, Spatial Distribution of the Network Structure in Epoxy Resin via the MAXS-CT Method, Langmuir, 10.1021/acs.langmuir.2c01741, 38, 37, 11432-11439, 2022.09, We have succeeded in visualizing the spatial heterogeneity of the reaction ratio in epoxy resins by combining medium-angle X-ray scattering (MAXS) and computed tomography (CT). The reaction ratio is proportional to the degree of cross-linking between epoxy and amine in epoxy resins. The reaction ratio and its spatial inhomogeneity affect the toughness of epoxy resins. However, there has been no non-destructive method to measure the spatial inhomogeneity of the reaction ratio, although we can measure only the spatially averaged reaction ratio by Fourier-transform infrared spectroscopy (FT-IR). We found that the scattering peak reflected the cross-linking structures in the q region of MAXS and that the peak intensity is proportional to the reaction ratio. By reconstructing CT images from this peak intensity, we visualized the spatial heterogeneity of the reaction ratio. The application of this method may not be limited to epoxy resins but may extend to studying the heterogeneity of cross-linked structures in other materials.. |
| 16. | H. K. Nguyen, A. Shundo, X. Liang, S. Yamamoto, K. Tanaka, K. Nakajima, Unraveling Nanoscale Elastic and Adhesive Properties at the Nanoparticle/Epoxy Interface Using Bimodal Atomic Force Microscopy, ACS Applied Materials and Interfaces, 10.1021/acsami.2c12335, 14, 37, 42713-42722, 2022.09, The addition of a small fraction of solid nanoparticles to thermosetting polymers can substantially improve their fracture toughness, while maintaining various intrinsic thermomechanical properties. The underlying mechanism is largely related to the debonding process and subsequent formation of nanovoids at a nanoscale nanoparticle/epoxy interface, which is thought to be associated with a change in the structural and mechanical properties of the formed epoxy network at the interface compared with the matrix region. However, a direct characterization of the local physical properties at this nanoscale interface remains significantly challenging. Here, we employ a recently developed bimodal atomic force microscopy technique for the direct mapping of nanoscale elastic and adhesive responses of an amine-cured epoxy resin filled with ∼50 nm diameter silica nanoparticles. The obtained elastic modulus and dissipated energy maps with high spatial resolution evidence the existence of a ∼20-nm-thick interfacial epoxy layer surrounding the nanoparticles, which exhibits a reduced modulus and weaker adhesive response in comparison with the matrix properties. While the presence of such a soft and weak-adhesive interfacial layer is found not to affect the architecture of structural heterogeneities in the epoxy matrix, it conceivably supports the toughening mechanism related to the debonding and plastic nanovoid growth at the silica/epoxy interface. The incorporation of this soft interfacial layer into the Halpin–Tsai model also provides a good explanation for the effect of the silica fraction on the tensile modulus of cured epoxy nanocomposites.. |
| 17. | C. Wang, T. Hashimoto, Y.-C. Chuang, K. Tanaka, Y.-P. Chang, T.-W. Yang, M.-T. Huang, Physical Gelation of Aqueous Solutions of Atactic Poly(N-isopropylacrylamide), Macromolecules, 10.1021/acs.macromol.1c02476, 55, 20, 9152-9167, 2022.09, Aqueous solutions of atactic poly(N-isopropylacrylamide) (PNIPAM) exhibit complex phase transitions at 20–33 °C, that is, the phase behaviors of lower critical solution temperature (LCST) and physical gelation. The LCST phase behavior has been successfully described by the “pearl-necklace” chain model (Macromolecules 2005, 38, 4465); however, the formation of the physical gel is still elusive. In this study, atactic PNIPAM (a-PNIPAM) was used and the gel point (GP) of semidilute solutions was validated by observing the frequency-independent loss tangent (Winter–Chambon criterion) from the oscillatory shear measurements to derive the gel temperature Tgel. It was found that the relaxation exponent n at GP is independent of solution concentration to be 0.76 with the fact that entanglement couplings play no effect on n. Tgel decreases with a-PNIPAM concentration from 29.5 °C for the 5 wt % unentangled solution to 25 °C for the 12 wt % entangled solution. The binodal point (Tb) was obtained from the extrapolated cloud-point temperature at zero heating rate, at which an initial drop of the light transmittance was observed. Based on these derived data, a phase diagram was constructed to show three typical phase domains composed of an one-phase solution at T Tb. At 30 °C, the clear gels of 5 and 12 wt % samples possess extremely low equilibrium moduli of 0.2 and 41 Pa, respectively, suggesting that many a-PNIPAM single chains are associated and connected in between two gel junctions. Synchrotron small-angle/wide-angle X-ray scattering was performed to disclose the radius of gyration of gel junctions (with functionality f ≥ 3) to be 30–55 Å above Tgel. Within the gel junctions, the collapsed subchains (pearls), which belong to different chains, become more compact with the interchain distance decreasing from 15 Å at 20 °C to 11 Å at 30 °C for the 12 wt % solution. We proposed that the origin of physical gelation is relevant to the inter-amide hydrogen bonding between collapsed subchains in the gel junctions to develop a strong physical bonding for interchain connectivity. At an elevated temperature approaching the GP but still below the spinodal temperature, the physical crosslinking of the developing pregel clusters is further facilitated by the enhanced concentration fluctuations with a small-q Fourier-mode driven by the interchain associations, eventually giving rise to the critical gel at Tgel prior to solution phase separation.. |
| 18. | R. K. Bay, T. Zhang, S. Shimomura, M. Ilton, K. Tanaka, R. A. Riggleman, A. J. Crosby, Decoupling the Impact of Entanglements and Mobility on the Failure Properties of Ultrathin Polymer Films, Macromolecules, 10.1021/acs.macromol.2c01435, 55, 19, 8505-8513, 2022.09, The mechanical properties of glassy polymer thin films change as film thickness decreases below the average polymer molecule size. These changes have been associated with a reduction in interchain entanglements due to confinement and an increase in molecular mobility from the mobile surface layer. Here, using experiments and simulations, we determine how entanglements and surface mobility each individually impact the failure behavior of a glassy polymer film as the film becomes confined. We utilize a custom-built uniaxial tensile tester for ultrathin films and dark-field optical microscopy to characterize the complete stress–strain response and the associated strain localizations for ultrathin polystyrene films of varying thicknesses (h = 10 to 150 nm) for a range of molecular weights Mn of 61 to 2135 kDa. To directly correlate the changes in the molecular network to changes in the failure properties of ultrathin films, we perform nonequilibrium molecular dynamics simulations on N = 250, N = 60, with h = 10 to 30 films. From our results, accounting for both the changes in entanglements and mobility, we propose a semiempirical model that captures the failure response in both simulated and experimental glassy polymer thin films.. |
| 19. | S. Yamamoto, R. Kuwahara, K. Tanaka, Effects of Chemistry of Silicon Surfaces on the Curing Process and Adhesive Strength for Epoxy Resin, ACS Applied Polymer Materials, 10.1021/acsapm.2c00855, 4, 8, 6038-6046, 2022.07, The adhesive strength of epoxy resins is generally dependent on the surface chemistry of an adherend. Although the free space, or the nanoscopic void space, formed at the adhered interface due to the curing shrinkage is expected to have a significant impact on the adhesive strength, the molecular picture is not yet well understood. In this study, all-atom molecular dynamics simulations were used to investigate how the curing reaction and thereby adhesive strength of an epoxy resin differed on hydrophilic and hydrophobic silicon substrates. Before the reaction, a hardener of amine with a smaller molecular size was segregated at the silicon surface, and the extent became more remarkable on the hydrophilic surface with hydroxy groups that formed hydrogen bonds with amine. The epoxy resin shrank as the curing reaction proceeded, forming the overall 5-10% free space. The resin remained attached to the hydrophilic substrate, but was partly separated from the hydrophobic surface, resulting in the 15% free space in the 0.2 nm adhered interfacial region and thus a lesser contact area. Reflecting this, under tensile deformation, cohesive failure and interfacial delamination occurred for the hydrophilic and hydrophobic surfaces, respectively, under a yield stress of 200 MPa and a strain of 0.1. Our findings make it clear that the surface chemistry of an adherend was crucial for the adhesive strength of the epoxy resins via the microstructure formation at the interface.. |
| 20. | J.-H. Hong, H. Mokudai, T. Masaki, H. Matsuno, K. Tanaka, Water-induced Crystal Transition and Accelerated Relaxation Process of Polyamide 4 Chains in Microfibers, Biomacromolecules, 23, 8, 3458-3468, 2022.06, Microplastics have recently been identified as one of the major contributors to environmental pollution. To design and control the biodegradability of polymer materials, it is crucial to obtain a better understanding of the aggregation states and thermal molecular motion of polymer chains in aqueous environments. Here, we focus on melt-spun microfibers of a promising biodegradable plastic, polyamide 4 (PA4), with a relatively greater number density of hydrolyzable amide groups, which is regarded as an alternative to polyamide 6. Aggregation states and thermal molecular motion of PA4 microfibers without/with a post-heating drawing treatment under dry and wet conditions were examined by attenuated total reflectance-Fourier transform infrared spectroscopy and wide-angle X-ray diffraction analysis in conjunction with dynamic mechanical analysis. Sorbed water molecules in the microfibers induced the crystal transition from a meta-stable γ-form to a thermodynamically stable α-form via activation of the molecular motion of PA4 chains. Also, the post-drawing treatment caused a partial structural change of PA4 chains, from an amorphous phase to a crystalline phase. These findings should be useful for designing PA4-based structural materials applicable for use in marine environments.. |
| 21. | S. Nakamura, S. Yamamoto, Y. Tsuji, K. Tanaka, K. Yoshizawa, Theoretical Study on the Contribution of Interfacial Functional Groups to the Adhesive Interaction between Epoxy Resins and Aluminum Surfaces, Langmuir, 10.1021/acs.langmuir.2c00529, 38, 21, 6653-6664, 2022.05, To ensure the quality and reliability of products bonded by epoxy resin adhesives, elucidation of the microscopic adhesion mechanism is essential. The adhesive interaction and bonding strength between epoxy resins and hydroxylated γ-alumina (001) surfaces were investigated by using a combined molecular dynamics (MD) and density functional theory (DFT) study. The curing reaction of an epoxy resin consisting of diglycidyl ether of bisphenol A (DGEBA) and 4,4′-diaminodiphenyl sulfone (DDS) was simulated. The resin structure was divided into fragmentary structures to study the interaction of each functional group with the alumina surface using DFT calculations. From the characteristics of the adhesive structures and the calculated adhesion energies, it was found that the fragments forming hydrogen bonds with hydroxy groups on the alumina surface resulted in large adhesion energies. On the other hand, the fragments adsorbed on the alumina surface via dispersion interactions resulted in small adhesion energies. The adhesion forces evaluated from the Hellmann–Feynman force calculations indicated the significant contribution of the hydroxy groups and benzene ether moieties derived from DGEBA to the adhesive stress of the DGEBA/DDS epoxy resin. The direction of hydrogen bonding between the epoxy resin and the surface and the difference in geometry at the interface between the donor and acceptor of hydrogen bonding played a central role in maintaining the adhesive strength during the failure process of the adhesive interface.. |
| 22. | R. Harada, D. Kawaguchi, S. Yamamoto, K. Tanaka, Change in Local Conformation of Polymer Chains at Film Surface Attached to Solid Surface, Soft Matter, 10.1039/d1sm01833g, 18, 17, 3304-3307, 2022.04, Adhesion is a molecular event where polymer chains contact with a material surface to form an interfacial layer. To obtain a better understanding of the adhesion on a molecular scale, we herein examined the conformational change of polystyrene (PS) chains at the film surface after contacting with hydrophobic or hydrophilic surfaces using sum-frequency generation (SFG) spectroscopy. Chains altered their local conformations with a quartz surface more quickly than a hydrophobic alkyl-functionalized one. A full-atomistic molecular dynamics simulation showed that these results, which were coupled with the contact process of PS chains with the solid surface, could be explained in terms of the Coulomb interaction between them.. |
| 23. | M. Inutsuka, H. Watanabe, M. Aoyagi, N. L. Yamada, C. Tanaka, T. Ikehara, D. Kawaguchi, S. Yamamoto, K. Tanaka, Effect of Oligomer Segregation on the Aggregation State and Strength at the Polystyrene/Substrate Interface, ACS Macro Lett., 10.1021/acsmacrolett.2c00062, 11, 4, 504-509, 2022.03, The interfacial strength of polystyrene (PS) with and without PS oligomers in contact with a glass substrate was examined to determine the relationship between the interfacial aggregation state and adhesion. The shear bond strength and adsorbed layer thickness of neat PS exhibited a similar dependence on the thermal annealing time: they increased to constant values within almost the same time. This implies that the adhesion of the polymer is closely related to the formation of an adsorbed layer at the adhesion interface. Nevertheless, in the case of PS with a small amount of oligomer, the shear bond strength decreased, while the adsorbed layer thickness was almost the same as that of neat PS. Based on the results of interfacial analyses, we propose that the interfacial segregation of the oligomer reduced the entanglement between the interfacial free chains in the adsorbed layer and the bulk chains.. |
| 24. | W. Ren, X. Wang, J. Shi, J. Xu, H. Taneda, N. L. Yamada, D. Kawaguchi, K. Tanaka, X. Wang, The Role of the Molecular Weight of the Adsorbed Layer at a Substrate in the Suppressed Dynamics of Supported Thin Polystyrene Films, Soft Matter, 10.1039/D2SM00067A, 18, 10, 1997-2005, 2022.03, The adsorbed layer on a solid surface plays a crucial role in the dynamics of nanoconfinement polymer materials. However, the influence of the adsorbed layer is complex, and clarifying this influence on the dynamics of confined polymers remains a major challenge. In this paper, SiO2-Si substrates with various thicknesses and adsorbed layers of PS with various molecular weights were used to reveal the effect of the adsorbed layer on the corresponding segmental dynamics of the supported thin PS films. Strongly suppressed segmental dynamics of thin PS films were observed for the films supported on thicker adsorbed layers or prepared using higher molecular weight. Neutron reflectivity revealed that the overlap region thickness between the adsorbed layer and the top overlayer increased with increasing thickness and molecular weight of the adsorbed layer, both of which correlate well with the distance over which the polystyrene dynamics were depressed by the adsorbed layer. The results show that the influencing distance of the adsorbed layer is related to the overlap zone formed between the adsorption layer and the upper thin film. The effect of the adsorbed layer molecular weight can be ascribed to the fact that large loops and long tails in the adsorbed layer result in stronger interpenetrations and entanglements between polymer chains in the adsorbed layer and in the overlayer, causing a stronger substrate effect and suppression of the segment dynamics of the supported thin PS films.. |
| 25. | T. Abe, H. Shimada, T. Hoshino, D. Kawaguchi, K. Tanaka, Sum Frequency Generation Imaging for Semi-Crystalline Polymers, Polym. J., 10.1038/s41428-021-00613-9, 54, 5, 679-685, 2022.01, Sum-frequency generation (SFG) spectroscopy is a powerful tool to study the molecular orientation in confined systems such as interfaces on the basis of the second-order nonlinear optical effect. We herein demonstrated SFG imaging for films of uniaxially oriented poly(vinylidene fluoride) and spin-coated isotactic polypropylene and successfully identified the orientational difference of lamellar fibrils in the two films. SFG chemical mapping was finally performed by taking advantage of the different absorption wavelengths for methylene groups in the two samples. To the best of our knowledge, this is the first report dealing with SFG mapping for synthetic polymers.. |
| 26. | L. Bai, P. Luo, X. Yang, J. Xu, D. Kawaguchi, C. Zhang, N. L. Yamada, K. Tanaka, W. Zhang, X. Wang, Enhanced Glass Transition Temperature of Thin Polystyrene Films Having an Underneath Cross-Linked Layer, ACS Macro Lett., 10.1021/acsmacrolett. 1c00611, 11, 2, 210-216, 2022.01, Due to the importance of the interface in the segmental dynamics of supported macromolecule ultrathin films, the glass transition temperature (Tg) of polystyrene (PS) ultrathin films upon solid substrates modified with a cross-linked PS (CLPS) layer has been investigated. The results showed that the Tg of the thin PS films on a silica surface with a ∼5 nm cross-linked layer increased with reducing film thickness. Meanwhile, the increase in Tg of the thin PS films became more pronounced with increasing the cross-linking density of the layer. For example, a 20 nm thick PS film supported on CLPS with 1.8 kDa of cross-linking degree exhibited a ∼35 and ∼50 K increase in Tg compared to its bulk and that on neat SiO2 substrate, respectively. Such a large Tg elevation for the ultrathin PS films was attributed to the interfacial aggregation states in which chains diffused through nanolevel voids formed in the cross-linked layer to the SiO2–Si surface. In such a situation, the chains were topologically constrained in the cross-linked layer with less mobility. These results offer us the opportunity to tailor interfacial effects by changing the degree of cross-linking, which has great potential application in many polymer nanocomposites.. |
| 27. | 甲加晃一, 日笠茂樹, 織田ゆか里, 川口大輔, 田中敬二, ポリプロピレン系複合材料の引張特性に及ぼす無水マレイン酸変性ポリプロピレンの添加効果, 日本接着学会誌, 58, 1, 29-35, 2022.01, ポリプロピレン(PP)/フィラー複合材料に無水マレイン酸変性ポリプロピレン(PP-g-MA)を添加した際の引張降伏応力(σy)について検討した。フィラーとして,同程度の平均粒子径を有する球状シリカ(SiO2)または球状アルミナ(Al2O3)を用いた。Al2O3系複合材料はSiO2系よりも大きなσyを示した。また,PP-g-MAとフィラーを混合した後,PP-g-MAを溶かし出した試料の熱重量測定を行った。Al2O3上に吸着したPP-g-MA鎖の熱分解に由来する重量減少は,SiO2上のそれよりも顕著であった。この結果は,PP-g-MAは,SiO2よりAl2O3上により吸着すること,すなわち,PP-g-MAはAl2O3とより強く相互作用することを示している。以上の結果は,高分子系複合材料にマトリックスとフィラー両方に強く相互作用する第三成分を添加することは,フィラー界面,ひいては,複合材料の力学特性を改善する有効な戦略であると結論できる。. |
| 28. | P. Wang, R. Maeda, M. Aoki, T. Kubozono, D. Yoshihara, A. Shundo, T. Kobayashi, S. Yamamoto, K. Tanaka, S. Yamada, In-situ Transmission Electron Microscopy Observation of the Deformation and Fracture Processes of an Epoxy/silica Nanocomposite, Soft Matter, 10.1039/D1SM01452H, 18, 6, 1149-1153, 2021.12, Herein, we report the in situ transmission electron microscopy observation of the deformation and fracture processes of an epoxy resin thin film containing silica nanoparticles under tensile strain. Under tensile strain, the dispersed silica nanoparticles in the composite arrest the progress of the crack tip and prevent crack propagation. Concomitantly, the generation and growth of nanovoids at the epoxy matrix/nanoparticle interfaces were clearly observed, particularly in the region near the crack tip. These nanovoids contribute to the dissipation of fracture energy, thereby enhancing the fracture toughness. We also analyzed the local distributions of the true strain and strain rate in the nanocomposite film during tensile testing using the digital image correlation method. In the region around the crack tip, the strain rate increased by 3 to 10 times compared to the average of the entire test specimen. However, the presence of large filler particles in the growing crack suppressed the generation of strain, potentially contributing to hindering crack growth.. |
| 29. | H. Taneda, N. L. Yamada, F. Nemoto, Y. Minagawa, H. Matsuno, K. Tanaka, Modification of a Polymer Surface by Partial Swelling Using Non-solvents, Langmuir, 10.1021/acs.langmuir.1c02852, 37, 51, 14941-14949, 2021.12, Surface modification without changing the physical properties in the bulk is of pivotal importance for the development of polymers as devices. We recently proposed a simple surface functionalization method for polymer films by partial swelling using a nonsolvent and demonstrated the incorporation of poly(2-methoxyethyl acrylate) (PMEA), which has an excellent antibiofouling ability, only into the outermost region of a poly(methyl methacrylate) (PMMA) film. We here extend this technology to another versatile polymer, polystyrene (PS). In this case, PS and PMEA have different solubility parameters making it difficult to select a suitable solvent, which is a nonsolvent for PS and a good solvent for PMEA, unlike the combination of PMMA with PMEA. Thus, such a solvent was first sought by examining the swelling behavior of PS films in contact with various alcohols. Once a mixed solvent of methanol/1-butanol (50/50 (v/v)) was chosen, PMEA chains could be successfully incorporated at the outermost region of the PS film. Atomic force microscopy in conjunction with neutron reflectivity revealed that chains of PMEA incorporated in the PS surface region were well swollen in water. This leads to an excellent ability to suppress the adhesion of platelets on the PS film.. |
| 30. | K. Kawabata, M. Totani, D. Kawaguchi, H. Matsuno, K. Tanaka, Two-Dimensional Cellular Patterning on a Polymer Film Based on Interfacial Stiffness, Langmuir, 10.1021/acs.langmuir.1c02776, 37, 51, 14911-14919, 2021.12, The mechanical properties in the outermost region of a polymer film strongly affect various material functions. We here propose a novel and promising strategy for the two-dimensional regulation of the mechanical properties of a polymer film at the water interface based on an inkjet drawing of silica nanoparticles (SNPs) underneath it. A film of poly(2-hydroxyethyl methacrylate) (PHEMA), which exhibits excellent bioinertness properties at the water interface, was well fabricated on a substrate with a pattern of SNPs. X-ray photoelectron spectroscopy and atomic force microscopy confirmed that the surface of the PHEMA film was flat and chemically homogeneous. However, the film surface was in-plane heterogeneous in stiffness due to the presence of the underlying SNP lines. It was also noted that NIH/3T3 fibroblast cells selectively adhered and formed aggregates on the areas under which an SNP line was drawn.. |
| 31. | H. K. Nguyen, M. Aoki, X. Liang, S. Yamamoto, K. Tanaka, K. Nakajima, Local Mechanical Properties of Heterogeneous Nanostructures Developed in a Cured Epoxy Network: Implications for Innovative Adhesion Technology, ACS Appl. Nano Mater., 10.1021/acsanm.1c02692, 4, 11, 12188-12196, 2021.10, The physical performance of an epoxy-based material is largely influenced by the formation of heterogeneous nanostructures (HNSs) in the glassy three-dimensional epoxy network. Thus, understanding the connectivity and local mechanical properties of HNSs formed in cured epoxy networks is of critical importance in the development of advanced epoxy-based materials for innovative adhesion technology. Here, we use bimodal atomic force microscopy (AFM) to map the local mechanical responses of HNSs evolved in an epoxy–amine system during curing. Both modulus and dissipated energy quantities describing the elastic and adhesive responses, respectively, were simultaneously obtained at different harmonic vibrations in each bimodal AFM measurement. HNSs exhibiting different elastic and adhesive responses were clearly visualized for all epoxy networks at different levels of curing. The architecture and local mechanical responses of HNSs were visibly altered with increasing degree of conversion. Soft domains representing network regions with relatively lower elastic moduli and weaker adhesive interactions were dominant and continuously connected at initial stages of curing up to conversion degrees of ∼91%. However, hard domains became increasingly connected upon approaching the fully cured stage. In combination with previously reported results obtained using the particle tracking technique to study the network heterogeneity at lower conversion degrees of the same epoxy system, we were able to provide a full picture describing the generation and development of mechanical heterogeneities in the network during curing in which the length scale of the heterogeneities decreased from several hundred nanometers at the pregelation stage to ∼10 nm at the fully cured stage.. |
| 32. | D. Kawaguchi, K. Yamamoto, T. Abe, N. Jiang, T. Koga, S. Yamamoto, K. Tanaka, Local Orientation of Chains at Crystal/Amorphous Interfaces Buried in Isotactic Polypropylene Thin Films, Physical Chemistry Chemical Physics, 10.1039/D1CP03959H, 23, 41, 23466-23472, 2021.10. |
| 33. | A. Shundo, M. Aoki, S. Yamamoto, K. Tanaka, Effect of Cross-linking Density on Horizontal and Vertical Shift Factors in Linear Viscoelastic Functions of Epoxy Resins, Macromolecules, 10.1021/acs.macromol.1c01293, 54, 20, 9618-9624, 2021.10. |
| 34. | Y. Tomo, H. Koga, T. Fukunaga, K. Kurata, H. Matsuno, K. Tanaka, H. Takamatsu, Thermal Conductivity Measurement of Solid Materials Using an “ITX” Method–A Pilot Study Using DNA Solid Films, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2021.121501, 176, 2021.09, A new method is proposed to measure the longitudinal thermal conductivity of fibers and films. The thermal conductivity of novel one- and two-dimensional materials has previously been measured using a T-type probe. Although this method is applicable to polymer fibers and films, the measurements are influenced by the thermal contact resistance between the probe and the sample. We therefore propose a so-called ITX method, which determines the inherent thermal conductivity of a sample from measurements made in three geometric configurations (“I”, “T”, and “X” shape) of the sample, heat sinks, and measurement probe. Application of the method to DNA solid films demonstrated that the thermal conductivity can be accurately determined irrespective of the relative contribution of the thermal contact resistance to the overall thermal resistance.. |
| 35. | Z. Hao, A. Ghanekarade, N. Zhu, K. Randazzo, D. Kawaguchi, K. Tanaka, X. Wang, D. S. Simmons, R. D. Priestley, B. Zuo, Mobility Gradients Yield Rubbery Surfaces on Top of Polymer Glasses, Nature, 10.1038/s41586-021-03733-7, 596, 7872, 372-376, 2021.08, ナノクリープ実験に基づき、高分子ガラス表面では分子鎖の長さに依存しない絡み合いセグメントが存在することを観測しました。従来は、高分子鎖の絡み合いはその長さのみで規定されると考えられていましたが、本研究では、高分子表面に存在する分子鎖が内部領域まで繋がるため、表面近傍でセグメントが緩和しても疑似ループコンフォメーションが形成され、短い分子鎖でも一時的に絡み合ったような粘弾性挙動を示すことを明らかにしました。. |
| 36. | A. Shundo, M. Aoki, S. Yamamoto, K. Tanaka, Cross-Linking Effect on Segmental Dynamics of Well-Defined Epoxy Resins, Macromolecules, 10.1021/acs.macromol.1c00513, 54, 13, 5950-5956, 2021.07, Epoxy resins with a network structure, which are obtained by curing reactions of epoxy and amine compounds, are an important class of thermosetting resins. We here report the segmental dynamics of epoxy resins in which the three-dimensional network was well-defined and systematically varied. What we found by experiments in conjunction with atomistic molecular dynamics simulation was that when the cross-linking density in the epoxy resins increased, the glass transition temperature increased with an associated reduction in the spatial scale of the cooperative rearranging region and the increase in the dynamic heterogeneity. The knowledge here obtained should be useful for a better understanding of the physical properties of thermosetting polymers.. |
| 37. | D. Kawaguchi, K. Sasahara, D. Saito, M. Uejima, H. Fujiwara, S. Nishimura, S. Yamamoto, K. Tanaka, Molecular Picture of Fluoropolymer Adsorption on Nanocarbon Materials, Polym. J., 10.1038/s41428-021-00528-5, 53, 12, 1469-1473, 2021.07. |
| 38. | S. Yamamoto, R. Kuwahara, K. Tanaka, Dynamic Behaviour of Water Molecules in Heterogeneous Free Space Formed in An Epoxy Resin, Soft Matter, 10.1039/D1SM00529D, 17, 25, 6073-6080, 2021.07. |
| 39. | T. Abe, D. Kawaguchi, M. Watanabe, T. Hoshino, T. Ishihara, K. Tanaka, An Effect of Crystallographic Distortion on Carrier Mobility in Poly(3-hexylthiophene) Thin Films, Applied Physics Letters, 10.1063/5.0041881, 118, 18, 181601-1-181601-5, 2021.05. |
| 40. | F. Wang, Z. Jiang, X. Lin, C. Zhang, K. Tanaka, B. Zuo, W. Zhang, X. Wang, Suppressed Chain Entanglement Induced by Thickness of Ultrathin Polystyrene Films, Macromolecules, 10.1021/acs.macromol.1c00224, 54, 8, 3735-3743, 2021.04, The thickness effect on the relaxation behavior and chain entanglements was investigated for thin polystyrene films. By following the time evolution of the wetting ridge at the surface induced by a droplet of ionic liquid, the characteristic time (tau*) at which the ridge height started to change was obtained. Here, we demonstrated experimentally that the characteristic time was associated with the disentanglement time tau(d), tau* similar to tau(d) similar to M-w(3.4)/M-e(1.4), where M-e denotes the entanglement molecular weight. The critical thickness (h(c)) at which tau* started to decrease was approximately 3.3R(g). That is, the M-e increased, or the interchain entanglement density decreased, as the film became thinner than the h(c). This might be explained in terms of the conformational change from "spherical" to "ellipsoidal", leading to a reduction in the pervaded volume (V-p) of chains in the ultrathin films.. |
| 41. | S. Yamamoto, K. Tanaka, Molecular Size Effect on Curing Process for Epoxy and Amine Mixture, 日本レオロジー学会誌, 10.1678/rheology.49.55., 49, 2, 55-60, 2021.04. |
| 42. | J.-H. Hong, M. Totani, T.Yamamoto, P. M. Dietrich, A. Thissen, H. Matsuno, K. Tanaka, Near-ambient Pressure X-ray Photoelectron Spectroscopy for a Bioinert Polymer Film at a Water Interface, Polym. J., 10.1038/s41428-021-00485-z, 53, 8, 907-912, 2021.04, A better understanding of the aggregation states of polymers in contact with water is a pivotal issue for the development of highly functional polymer devices that work under water. As a direct experimental method to achieve the above, we used near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) on a poly(methyl methacrylate) (PMMA) film mixed with a small amount of a bottlebrush-type methacrylate polymer with oligo(2-ethyl-2-oxazoline) in its side chain portions, referred to as P[O(Ox)(n)MA], in a hydrated state. The results showed that P[O(Ox)(n)MA] was segregated at the surface of the PMMA film and suppressed the adhesion and activation of platelets on the film.. |
| 43. | S. Yamamoto, K. Tanaka, Entropy-Driven Segregation in Epoxy-Amine Systems at a Copper Interface, Soft Matter, 10.1039/D0SM01600D, 17, 5, 1359-1367, 2021.02. |
| 44. | J.-H. Hong, M. Totani, D. Kawaguchi, N. L. Yamada, H. Matsuno, K. Tanaka, Poly[oligo(2-ethyl-2-oxazoline) methacrylate] as a Surface Modifier for Bioinertness, Polym. J., 10.1038/s41428-020-00459-7, 53, 5, 643-653, 2021.01. |
| 45. | Y. Oda, D. Kawaguchi, Y. Morimitsu, S. Yamamoto, K. Tanaka, Direct Observation of Morphological Transition for an Adsorbed Single Polymer Chain, Scientific Reports, 10.1038/s41598-020-77761-0, 10, 20914, 2020.12, A better understanding of the structure of polymers at solid interfaces is crucial for designing various polymer nano-composite materials from structural materials to nanomaterials for use in industry. To this end, the first step is to obtain information on how synthetic polymer chains adsorb onto a solid surface. We closely followed the trajectory of a single polymer chain on the surface as a function of temperature using atomic force microscopy. Combining the results with a full-atomistic molecular dynamics simulation revealed that the chain became more rigid on the way to reaching a pseudo-equilibrium state, accompanied by a change in its local conformation from mainly loops to trains. This information will be useful for regulating the physical properties of polymers at the interface.. |
| 46. | K. Uchida, K. Mita, S. Yamamoto, K. Tanaka, Local Orientation of Polystyrene at the Interface with Poly(methyl methacrylate) in Block Copolymer, ACS Macro Letters, 10.1021/acsmacrolett.0c00638, 9, 11, 1576-1581, 2020.11, The local conformation of polystyrene (PS) at the phase-separated lamellar interface with poly(methyl methacrylate) (PMMA) in their diblock copolymer (BCP) was examined by sum-frequency generation spectroscopy in conjunction with a full-atomistic molecular dynamics simulation. While PS phenyl groups of BCP were oriented in the interfacial region, they were random in the bulk. Such an interfacial orientation of phenyl groups was not clear for the corresponding blend of PS and PMMA. The PS backbone of BCP was in-plane oriented and folded near to the chemical junction point located in the interfacial region and the orientation became random at several nanometers distant. No evidence for the chain folding at the interface was found for the blend system.. |
| 47. | T. Kogo, A. Shundo, C. Wang and K. Tanaka, Spatial Heterogeneity Accompanying Gel Formation of Poly(N-isopropylacrylamide) Aqueous Solution at a Temperature below Cloud Point, Macromolecules, 10.1021/acs.macromol.0c02292, 53, 24, 10964-20971, 2020.11. |
| 48. | J.-H. Hong, M. Totani, D. Kawaguchi, H. Masunaga, N. L. Yamada, H. Matsuno, K. Tanaka, Design of a Bioinert Interface Using an Amphiphilic Block Copolymer Containing a Bottlebrush Unit of Oligo(oxazoline), ACS Applied Bio Materials, 10.1021/acsabm.0c01118, 3, 11, 7363-7368, 2020.10, We designed an amphiphilic block copolymer, poly(methyl methacrylate)-block-poly[oligo(2-ethyl-2-oxazoline) methacrylate] (PMMA-b-P[O(Ox)MA]), suitable for bioinert coating. Angular-dependent X-ray photoelectron spectroscopy and neutron reflectivity measurements revealed that the outermost surface of a dried film of PMMA-b-P[O(Ox)MA] was covered with the PMMA block-rich layer. Once the film came into contact with water, the P[O(Ox)MA] bottlebrush block was segregated toward the water interface. This structural rearrangement in the outermost region of the film resulted in the formation of the swollen oligo(oxazoline) layer with excellent bioinertness in terms of the suppression of serum protein adsorption and NIH3T3 fibroblast adhesion.. |
| 49. | M. Aoki, A. Shundo, S. Yamamoto, K. Tanaka, Effect of a Heterogeneous Network on Glass Transition Dynamics and Solvent Crack Behavior of Epoxy Resins, Soft Matter, 10.1039/d0sm00625d, 16, 32, 7470-7478, 2020.08. |
| 50. | M. Ikeda, A. Kuzuya, M. Matsusaki, K. Tanaka, Special issue: Biofunctional Gels, Polym. J., 10.1038/s41428-020-0360-7, 52, 8, 821-821, 2020.08. |
| 51. | K. Yamamoto, D. Kawaguchi, T. Abe, T. Komino, M. Mamada, T. Kabe, C. Adachi, K. Naka, K. Tanaka, Surface Segregation of a Star-Shaped Polyhedral Oligomeric Silsesquioxane in a Polymer Matrix, Langmuir, 10.1021/acs.langmuir.0c01785, 36, 33, 9960-9966, 2020.08, A simple way to control only the surface properties of polymer materials, without changing the bulk properties, has long been desired. The segregation behavior when a component with a tiny amount fed into the matrix is thermodynamically enriched at the surface is one of the candidate methods. This capability was examined herein by focusing on a star-shaped polyhedral oligomeric silsesquioxane (s-POSS), where the central POSS unit is tethered to eight isobutyl-substituted POSS cages as a surface modifier. X-ray photoelectron spectroscopy revealed that the surface of a film of poly(methyl methacrylate) (PMMA) was almost completely covered with POSS units by adding just 5 wt % s-POSS to it. The segregated POSS dramatically altered the physical properties such as molecular motion and the mechanical and dielectric responses at the surface of the PMMA film. These findings make it clear that s-POSS is an excellent surface modifier for glassy polymers.. |
| 52. | Y. Wu, A. Shundo, Y. Yasukochi, K. Tanaka, Time-dependent Heterogeneity in Polyacrylic Pressure Sensitive Adhesive, European Polymer Journal, 10.1016/j.eurpolymj.2020.109812, 134, 2020.07, [URL]. |
| 53. | H. K. Nguyen, D. Kawaguchi, K. Tanaka, Effect of Molecular Architecture on Conformational Relaxation of Polymer Chains at Interfaces, Macromolecular Rapid Communications, 10.1002/marc.202000096, 41, 21, 2020.05, Dynamics of polymer chains near an interface with an inorganic material are believed to strongly affect the physical properties of polymers in nanocomposites and thin films. An effect of molecular architecture on the conformational relaxation behavior of polystyrene (PS) chains at the quartz interface using sum-frequency generation spectroscopy is reported here. The relaxation dynamics of chains in direct contact with the quartz interface is slower with a star-shaped architecture than that with its linear counterpart. The extent of the delay becomes more pronounced with increasing number of arms. This can be explained in terms of the superior interfacial activity to the quartz surface for the star-shaped PS.. |
| 54. | A. Shundo, Y. Matsumoto, H. Hayashi, N. Tsuruzoe, H. Matsuno, K. Tanaka, Mesoscopic Heterogeneity in a Nanocellulose-Containing Cell Storage Medium, Journal of Materials Chemistry B, 10.1039/d0tb00219d, 2020.04, [URL]. |
| 55. | Y. Oda, M. Inutsuka, R. Awane, M. Totani, N. L. Yamada, M. Haraguchi, M. Ozawa, H. Matsuno, K. Tanaka, A Dynamic Interface Based on Segregation of an Amphiphilic Hyperbranched Polymer Containing Fluoroalkyl and Oligo(ethylene oxide) Moieties, Macro Molecules, 10.1021/acs.macromol.9b02064, 53, 7, 2380-2387, 2020.03. |
| 56. | T. Hirata, H. Taneda, K. Nishio, M. Inutsuka, N. L. Yamada, F. Nemoto, Y. Minagawa, H. Matsuno, K. Tanaka, A Facile Surface Functionalization Method for Polymers Using a Nonsolvent, ACS Applied Bio Materials, 10.1021/acsabm.0c00028, 2020.03. |
| 57. | T. Miyazaki, N. Miyata, T. Yoshida, H. Arima, Y. Tsumura, N. Torikai, H. Aoki, K. Yamamoto, T. Kanaya, D. Kawaguchi, K. Tanaka, Detailed Structural Study on the Poly(vinyl alcohol) Adsorption Layers on a Si Substrate with Solvent Vapor-Induced Swelling, Langmuir, 10.1021/acs.langmuir.9b03964, 36, 13, 3415-3424, 2020.03. |
| 58. | Y. Morimitsu, H. Matsuno, N. Ohta, H. Sekiguchi, A. Takahara, K. Tanaka, Mechanical Stabilization of Deoxyribonucleic Acid Solid Films Based on Hydrated Ionic Liquid, Bio Macro Molecules, 10.1021/acs.biomac.9b01207, 21, 2, 464-471, 2020.02. |
| 59. | S. Yamamoto, R. Kuwahara, M. Aoki, A. Shundo, K. Tanaka, Molecular Events for an Epoxy-Amine System at a Copper Interface, ACS Applied Polymer Materials, 10.1021/acsapm.9b01154, 2, 4, 1474-1481, 2020.02, Epoxy is a class of thermosetting resins and has been widely used as a representative example of structural adhesives. Nevertheless, it remains unclear how the epoxy resin and curing agent are present on the adherend surface and how they move around dynamically and react with each other to form a three-dimensional network. We here adopt a fully atomistic molecular dynamics (MD) simulation to study molecular events of an epoxy resin composed of hydrogenated bisphenol A diglycidyl ether and 1,4-cyclohexanebis(methylamine) at the interface using a narrow gap, which was sandwiched between copper surfaces. The depth profiles of the density, molecular orientation, and concentration in addition to molecular diffusivity at the interface are addressed. These are finally combined with the kinetics for the curing reactions at the interface. Although some of the information here obtained is accessible by experimentation, most is not. We believe that the findings of this study will lead to a better understanding of the adhesion phenomenon.. |
| 60. | K. Tanaka, PJ ZEON Award for Outstanding Papers in Polymer Journal 2019, Polym. J., 10.1038/s41428-020-0329-6, 52, 6, 551-553, 2020.01. |
| 61. | M. Ouchi, C. K. Luscombe, J. He, K. Tanaka, Special issue: Precision Polymer Synthesis, Polym. J., 10.1038/s41428-019-0276-2, 52, 1, 1-1, 2020.01. |
| 62. | N. Itagaki, D. Kawaguchi, Y. Oda, F. Nemoto, N. L. Yamada, T. Yamaguchi, K. Tanaka, Surface Effect on Frictional Properties for Thin Hydrogel Films of Poly(vinyl ether), Macromolecules, 10.1021/acs.macromol.9b01786, 2019.12, [URL], Frictional properties play a key role in the performance of hydrogels in applications such as soft contact lenses, cell sheets, artificial articular cartilage, etc. Here we characterize the swollen state and frictional properties of thin hydrogel films composed of poly(2-methoxyethyl vinyl ether) on a nanometer scale using neutron reflectivity (NR) in conjunction with lateral force microscopy, leading to the discussion about the extent to which surface chains impact the frictional properties of gels. NR measurement revealed that the density profile for the hydrogel films in the interfacial region with water along the direction normal to the interface was well described by a parabolic function, which was generally used for swollen polymer brushes in a liquid. Lateral, or frictional, force (FL) first increased with increasing normal force (FN) and then reached a region where the dependence of FL on FN was extremely subtle. That is, there exist two regimes, I and II, for the relationship between FN and FL. The thickness of the interfacial layer composed of dangling chains, which should behave like brush chains, as determined by NR measurement, was in good accordance with the depth at which the regime transited from region I to II. The frictional properties of the thin hydrogel films could be better understood by considering the two contributions from the interfacial layer and the internal bulk region.. |
| 63. | B. Zuo, Q. Xu, T. Jin, H. Xing, J. Shi, Z. Hao, L. Zhang, K. Tanaka, X. Wang, Suppressed Surface Reorganization in a High-Density Poly(methyl methacrylate) Brush, Langmuir, 10.1021/acs.langmuir.9b02581, 35, 46, 14890-14895, 2019.11, [URL], A high-density poly(methyl methacrylate) (PMMA) brush (σ = 0.77 chain/nm2) with a lower molecular weight distribution was prepared onto a silicon wafer by surface-initiated atom transfer radical polymerization. The surface of the PMMA brush chains was characterized upon the process of the environmental change, from air to water, using contact angle measurements in conjunction with sum-frequency generation spectroscopy. The surface structure and properties altered less with the changing environment from air to water for the PMMA brush than for a spin-coated film; that is, the extent of surface reorganization could be suppressed by grafting densely-packed chains onto a substrate. Also, the water penetration into the brush surface was inhibited because of the densely packed chain structure.. |
| 64. | Y. Matsumoto, A. Shundo, H. Hayashi, N. Tsuruzoe, K. Tanaka, Effect of the Heterogeneous Structure on Mechanical Properties for a Nanocellulose-Reinforced Polymer Composite, Macromolecules, 10.1021/acs.macromol.9b01866, 52, 21, 8266-8274, 2019.11, Nanocellulose (NC), which consists of a bundled structure of cellulose chains, is a class of shape-anisotropic materials with a diameter of several tens of nanometers and a length of over several hundreds of nanometers. Because the production of NC is based on the extraction process from natural resources in water, NC is generally obtained in an aqueous dispersion state. Thus, an aqueous dispersion of NC can be regarded as a precursor for NC-reinforced polymer composites. The objective of this study is to gain a better understanding of (1) local rheological properties of the NC aqueous dispersion at various length scales using a particle tracking measurement and (2) how they affect the mechanical properties of the resultant NC-reinforced polymer composite. The observation of individual particles at different positions revealed that the NC aqueous dispersion was spatially heterogeneous at the characteristic length of a few tens of micrometers. When the NC aqueous dispersion was sonicated and subsequently left undisturbed at room temperature, the length scale of the heterogeneity decreased. From the NC aqueous dispersion with and without the sonication treatment, having smaller and larger length scale of heterogeneity, respectively, poly(vinyl alcohol) (PVA) films containing NC were fabricated. The dispersion state of NC in the PVA matrix was improved by the prior sonication treatment. The addition of NC remarkably enhanced the ductility of the PVA film. However, this was the case only after the sonication treatment. The knowledge here obtained should provide a novel concept for polymer composites with tunable mechanical properties, based on the precursor-based design.. |
| 65. | Y. J. Jang, D. Kawaguchi, S. Yamaguchi, S. Lee, J. W. Lim, H. Kim, K. Tanaka, D. H. Kim, Enhancing the organic solar cell efficiency by combining plasmonic and FÖrster Resonance Energy Transfer (FRET) effects, Journal of Power Sources, 10.1016/j.jpowsour.2019.227031, 438, 2019.10, © 2019 Here, we combine two strategies i.e., Förster resonance energy transfer and plasmonic effect, to enhance the photovoltaic performance in organic solar cells by introducing gold nanoparticles and squaraine in a binary mixture of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester. In this configuration, the Förster resonance energy transfer between poly(3-hexylthiophene) and squaraine reduces the electrical loss arising from the exciton recombination in poly(3-hexylthiophene), while gold nanoparticles enable an efficient charge carrier generation in poly(3-hexylthiophene):squaraine mixture as optically confirmed by photoluminescence measurement and transient absorption spectroscopy. The multicomponent organic solar cells demonstrate an enhancement of ~36% in power conversion efficiency over the reference device.. |
| 66. | S. Lee, W. Lee, N. L. Yamada, K. Tanaka, J. H. Kim, H. Lee, D. Y. Ryu, Instability of Polystyrene Film and Thermal Behaviors Mediated by Unfavorable Silicon Oxide Interlayer, Macromolecules, 10.1021/acs.macromol.9b01284, 52, 19, 7524-7530, 2019.10, Instability, glass transition temperature (T-g), and thermal expansion of polystyrene (PS) films are evaluated with respect to the thickness of a silicon oxide (SiOx) interlayer that mediates favorable long-range interaction from the non-oxide Si substrate. Taking into account that a SiOx interlayer is less favorable with an overlying PS film, we designed a systematic set of H-passivated (H-Si), native SiOx (N-Si), and non-native SiOx interlayer (P-Si) substrates. Here, P-Si denotes a substrate prepared by a plasma surface activation with oxygen to create an effective minimum SiOx thickness (similar to 9 nm) that is sufficient for the instability of PS films. The wetting-dewetting behavior differs in 100 and 43 kg/mol PS films supported on the three different substrates. Reflected in T-g and thermal expansion coefficient at the rubbery state for the overlying PS films, P-Si is found to be enough to promote the nontrivial instability of the films, leading to a marked decrease in T-g and increase in alpha(r) with decreasing film thickness (more than those on N-Si). Our results demonstrate the ability to use P-Si to effectively modulate favorable long-range interaction from the Si substrate better than a typical N-Si does.. |
| 67. | S. Sugimoto, M. Inutsuka, D. Kawaguchi, K. Tanaka, The Effect of Interfacial Dynamics on the Bulk Mechanical Properties of Rubber Composites, Polym. J., 10.1038/s41428-019-0254-8, 52, 217-223, 2019.08. |
| 68. | M. K. Endoh, Y. Morimitsu, D. Salatto, Z. Huang, M. Sen, W. Li, Y. Meng, D. G. Thanass, J-M. Y. Carrillo, B. G. Sumpter, D. Kawaguchi, K. Tanaka, T. Koga, Protein Resistance Driven by Polymer Nanoarchitecture, ACS Macro Letters, 10.1021/acsmacrolett.9b00518, 8, 9, 1153-1159, 2019.08, We report that the nanometer-scale architecture of polymer chains plays a crucial role in its protein resistant property over surface chemistry. Protein-repellent (noncharged), few nanometer thick polymer layers were designed with homopolymer chains physisorbed on solids. We evaluated the antifouling property of the hydrophilic or hydrophobic adsorbed homopolymer chains against bovine serum albumin in water. Molecular dynamics simulations along with sum frequency generation spectroscopy data revealed the self-organized nanoarchitecture of the adsorbed chains composed of inner nematic-like ordered segments and outer brush-like segments across homopolymer systems with different interactions among a polymer, substrate, and interfacial water. We propose that this structure acts as a dual barrier against protein adsorption.. |
| 69. | H. K. Nguyen, S. Sugimoto, A. Konomi, M. Inutsuka, D. Kawaguchi, K. Tanaka, Dynamics Gradient of Polymer Chains near a Solid Interface, ACS Macro Letters, 10.1021/acsmacrolett.9b00351, 8, 8, 1006-1011, 2019.07, [URL], 石英界面におけるポリイソプレン鎖およびニトリルゴム鎖の緩和ダイナミクスをエバネッセント波励起蛍光偏光解消法、誘電緩和測定および和周波発生分光測定に基づき、界面からの距離の関数として評価した。その結果、界面層には分子鎖ダイナミクスの勾配が存在することを明らかにし、それが弱く吸着した鎖と強く吸着した鎖によるものと説明した。強く吸着した鎖の緩和はバルクのそれと比較して10桁以上遅くなることを示している。. |
| 70. | T. Miyazaki, N. Miyata, M. Asada, Y. Tsumura, N. Torikai, H. Aoki, K. Yamamoto, T. Kanaya, D. Kawaguchi, K. Tanaka, Elucidation of a Heterogeneous Layered Structure in the Thickness Direction of Poly(vinyl alcohol) Films with Solvent Vapor-Induced Swelling, Langmuir, 10.1021/acs.langmuir.9b01665, 35, 34, 11099-11107, 2019.07, [URL], We investigated the swelling behaviors of poly(vinyl alcohol) (PVA) films deposited on Si wafers with water vapor, which is a good solvent for PVA for elucidating structural and dynamical heterogeneities in the film thickness direction. Using deuterated water vapor, structural and dynamical differences in the thickness direction can be detected easily as different degrees of swelling in the thickness direction by neutron reflectivity. Consequently, the PVA film with a degree of saponification exceeding 98 mol % exhibits a three-layered structure in the thickness direction. It is considered that an adsorption layer consisting of molecular chains that are strongly adsorbed onto the solid substrate is formed at the interface with the substrate, which is not swollen with water vapor compared with the bulk-like layer above it. The adsorption layer is considered to exhibit significantly slower dynamics than the bulk. Furthermore, a surface layer that swells excessively compared with the underneath bulk-like layer is found. This excess swelling of the surface layer may be related to a higher mobility of the molecular chains or lower crystallinity at the surface region compared to the underneath bulk-like layer. Meanwhile, for the PVA film with a much lower degree of saponification, a thin layer with a slightly lower degree of swelling than the bulk-like layer above it can be detected at the interface between the film and substrate only under a high humidity condition. This layer is considered to be the adsorption layer composed of molecular chains loosely adsorbed onto the Si substrate.. |
| 71. | Y. Morimitsu, D. Salatto, N. Jiang, M. Sen, S. Nishitsuji, B. M. Yavitt, M. K. Endoh, A. Subramanian, C. Y. Nam, R. Li, M. Fukuto, Y. Zhang, L. Wiegart, A. Fluerasu, K. Tanaka, T. Koga, "Structurally Neutral" Densely Packed Homopolymer-Adsorbed Chains for Directed Self-Assembly of Block Copolymer Thin Films, Macromolecules, 10.1021/acs.macromol.9b00597, 52, 14, 5157-5167, 2019.07, [URL], We here report that adsorbed chains composed of one of the constituent blocks can be used as a new surface modification approach to induce perpendicularly oriented lamellar microdomains in block copolymer thin films. A nearly symmetric polystyrene-block-poly(methyl methacrylate) (PS-block-PMMA) diblock copolymer was used as a model. Densely packed PS- or PMMA-adsorbed chains of about 2-3 nm in thickness ("polymer nanocoatings") were deposited on silicon (Si) substrates using a solvent-rinsing approach. Spin-cast films of 40 or 60 nm-thick PS-block-PMMA (equivalent to two or three interdomain spacings) were subsequently deposited onto the PS or PMMA nanocoatings. Grazing incidence small-angle X-ray scattering experiments revealed the formation of perpendicularly oriented lamellar microdomains within the entire films at 200 °C, where balanced interfacial interactions at the polymer-air interface were achieved. Additionally, X-ray photon correlation spectroscopy studies demonstrated the dynamics of the fully standing lamellar microdomains in the melt, which are coupled to cooperative interdomain movement. We demonstrate that the "neutrality" of the nanocoating is attributed to its noninteractive property against both blocks. This "structurally neutral" property prevents adsorption of the PS-block-PMMA chains on the bare Si substrate that causes the undesirable substrate field effect.. |
| 72. | H. Matsuno, M. Totani, A. Yamamoto, M. Haraguchi, M. Ozawa, K. Tanaka, Water-induced Surface Reorganization of Bioscaffolds Composed of an Amphiphilic Hyperbranched Polymer, Polym. J., 10.1038/s41428-019-0212-5, 51, 10, 1045-1053, 2019.06, [URL], The ability to freely control the surface of bioscaffolds in a water environment is desirable to regulate cellular behaviors in vitro. Herein, we study the surface aggregation states of scaffold films composed of a multifunctional hyperbranched polymer (HBP) with perfluorohexylethyl, carboxy, and cyano groups that was prepared using a spin-coating method. Static contact angle measurements in conjunction with X-ray photoelectron spectroscopy revealed that perfluorohexylethyl groups were segregated at the surface of the HBP film in air, and these findings were more remarkable for the film treated with thermal annealing. Once the HBP film contacted water, HBP chains reorganized at the surface to minimize the free energy, resulting in the formation of a relatively hydrophilic surface. This surface reorganization was discernably faster and more remarkable for the non-annealed HBP film than for the annealed film. As fundamental characteristics of a cellular scaffold, protein adsorption, in addition to the initial adhesion and proliferation of fibroblasts, was examined using microscopy. The amount of fibronectin adsorbed depended on the presence of thermal annealing during the scaffold preparation process. A relatively larger amount of fibronectin adsorbed to the non-annealed HBP film promoted the initial adhesion and subsequent proliferation of fibroblasts.. |
| 73. | K. Tanaka, PJ ZEON Award for Outstanding Papers in Polymer Journal 2018, Polym. J., 10.1038/s41428-019-0188-1, 51, 6, 531-533, 2019.06, [URL]. |
| 74. | 松野寿生, 田中敬二, 水界面におけるバイオイナート高分子の凝集状態と熱運動特性, 高分子論文集, 10.1295/koron.2019-0013, 76, 3, 185-195, 2019.05, [URL], In this study, we prepared stable and flat surfaces of poly(2-methoxyethyl acrylate) (PMEA) which exhibit excellent bio-inert properties in a thin film state by blending it with poly(methyl methacrylate) (PMMA) and annealing at an appropriate temperature, higher than the glass transition temperature and lower than the phase-separation temperature of the blend. Furthermore, the aggregation state and thermal molecular motion of PMEA at the water interface were examined. After contacting with water, PMEA segregated to the water interface in the blend film. While the local conformation of PMEA at the water interface was insensitive to its molecular weight, the local dynamics became faster with decreasing molecular weight, resulting in a disturbance of the network structure of water molecules at the interface. This leads to the extreme suppression of protein adsorption and platelet adhesion.. |
| 75. | 町田悟史、近藤寛朗、仲山和海、大武義人、田中敬二, シリカ配合エチレンプロピレンゴムの熟成及び再混錬の加工性及び加硫後の物性への影響, プラスチック成型加工学会誌, 31, 5, 206-212, 2019.04. |
| 76. | R. Boppella, F. M. Mota, J. W. Lim, S. T. Kochuveedu, S. Ahn, J. Lee, D. Kawaguchi, K. Tanaka, D. H. Kim, Plasmon and Upconversion Mediated Broadband Spectral Response in TiO2 Inverse Opal Photocatalysts for Enhanced Photoelectrochemical Water Splitting, ACS Applied Energy Materials, 10.1021/acsaem.9b00469, 2, 5, 3780-3790, 2019.04, © 2019 American Chemical Society. Harvesting low-energy photons by strategically exploiting the photocatalytic properties of plasmonic and upconversion nanocomponents is a promising route to improve solar energy utilization. Herein, a rationally designed 3D composite photoanode integrating NIR-responsive upconversion nanocrystals (UCNs) and visible-responsive plasmonic Au nanoparticles (NPs) into 3D TiO2 inverse opal nanostructures (Au/UCN/TiO2) has been shown to extend the solar energy utilization in the UV-vis-NIR range. The NIR-responsive properties of NaYF4:Yb3+-based UCNs doped with Er3+ or Tm3+ ions, and the effect of an alternating sequential introduction of UCN and Au, have been assessed. With an extended overlap between the emission of Er-UCN and the characteristic SPR band of Au, our ternary Au/Er-UCN/TiO2 hybrid nanostructure unveiled a notable 10-fold improvement in photocurrent density under UV-vis-NIR illumination compared with a pristine TiO2 reference. The Au incorporation was confirmed to play a key role in enhancing the efficiency of light harvesting and to synergistically facilitate the energy transfer from UCNs to TiO2. This work further dissected plausible mechanistic pathways combining collected photoelectrocatalytic results, with electrochemical impedance measurements and transient absorption spectroscopic measurements. The synthesis and catalytic performance of our Au/UCN/TiO2 and the underlying mechanism here proposed are expected to reflect extended applicability in analogous applications for efficient solar-to-energy sustainable platforms.. |
| 77. | M. Inutsuka, M. Haraguchi, M. Ozawa, N. L. Yamada, K. Tanaka, Adhesion Control of Elastomer Sheet on the Basis of Interfacial Segregation of Hyperbranched Polymer, ACS Macro Letters, 10.1021/acsmacrolett.8b00971, 8, 3, 267-271, 2019.03, [URL], Adhesion of a model rubbery material, cross-linked poly(dimethylsiloxane) (PDMS), onto a solid surface was studied by sum-frequency generation spectroscopy and X-ray photoelectron spectroscopy. To do so, here, we have focused on the adhesive deposit and insoluble layer. The former and latter were defined as the residual amount on the substrate after the peeling and residual layer after washing with a good solvent, respectively. The peel strength of a PDMS sheet adhered onto a glass plate increased with the contact time. Both adhesive deposit and insoluble layer also exhibited comparable contact time dependence. Once a hyperbranched polymer (HBP), which was segregated to the adhesive interface, was incorporated into PDMS, the peel strength and adhesive deposit decreased, although the thickness of the insoluble layer remained almost unchanged. These results suggest that the formation of loosely adsorbed chains on the solid surface, which possess not only trains but also many loop portions and tail parts, plays an important role in the macroscopic adhesion behavior of the PDMS sheet and the interfacial segregation of HBP can prevent it.. |
| 78. | M. Aoki, A. Shundo, R. Kuwahara, S. Yamamoto, K. Tanaka, Mesoscopic Heterogeneity in the Curing Process of an Epoxy-Amine System, Macromolecules, 10.1021/acs.macromol.8b02416, 52, 5, 2075-2082, 2019.03, [URL], Epoxy resins are composed of a three-dimensional network formed by chemical reactions between epoxy and amino compounds, which plays an important role in the mechanical properties. Thus, to use epoxy resins in various applications, it is necessary to gain a better understanding of their network structure. Here, we study the structural heterogeneity evolved in an epoxy-amine mixture during the curing process on the basis of a particle tracking technique, in which the thermal motion of probe particles in the mixture was tracked, small-angle X-ray scattering measurements in conjunction with coarse-grained molecular dynamics simulation. The heterogeneous environment was generated even at the initial stage of the curing process. Notably, the characteristic length scale was on the order of several hundreds of nanometers down to several tens of nanometers, depending on the extent of curing. Once a reaction occurs between a pair of epoxy and amino groups, the temperature at the site is locally elevated due to the heat of formation, accelerating a subsequent reaction nearby. Repeating such a situation, actively and scarcely reacted domains are formed. This is the main origin of the structural heterogeneity in epoxy resins.. |
| 79. | M. Aoki, A. Shundo, K. Okamoto, T. Ganbe, K. Tanaka, Segregation of an Amine Component in a Model Epoxy Resin at a Copper Interface, Polym. J., 10.1038/s41428-018-0129-4, 51, 3, 359-363, 2019.03, [URL], © 2018, The Society of Polymer Science, Japan. Epoxy resins, which are obtained by the curing reaction of epoxy- and amine-compounds mixture, have been often utilized in contact with metals. We herein report on the chemical composition of the epoxy resin in close proximity to the copper interface on the basis of a non-destructive method. The concentration of the amine component in the interfacial region was 2-fold higher than that in the bulk, and the interfacial enrichment extended over at least 10 nm. [Figure not available: see fulltext.].. |
| 80. | M. Totani, L. Liu, H. Matsuno, K. Tanaka, Design of a Star-like Hyperbranched Polymer Having Hydrophilic Arms for Anti-biofouling Coating, Journal of Materials Chemistry B, 10.1039/c8tb03104e, 7, 7, 1045-1049, 2019.02, [URL], A star-like hyperbranched polymer having hydrophilic poly(ethyleneoxide acrylate) arms (HB-PEO9A) was prepared by a core-first method based on atom transfer radical polymerization. The PEO9A layer coated on a solid substrate was dissolved by water, and effectively inhibited protein adsorption and cell adhesion.. |
| 81. | K. Sakurai, M. Takenaka, K. Tanaka, Special issue Cutting Edge of Scattering from Softmaterials, Polym. J., 10.1038/s41428-018-0154-3, 51, 107, 2019.02, [URL]. |
| 82. | K. Yamamoto, D. Kawaguchi, K. Sasahara, M. Inutsuka, S. Yamamoto, K. Uchida, K. Mita, H. Ogawa, M. Takenaka, K. Tanaka, Aggregation States of Poly(4-methylpentene-1) at a Solid Interface, Polym. J., 10.1038/s41428-018-0134-7, 51, 2, 247-255, 2018.11, [URL], A thin film of poly(4-methylpentene-1) (P4MP1) was prepared on a quartz substrate, which was a model system of an interface in filler-reinforced semicrystalline polymer composites. Grazing-incidence wide-angle X-ray diffraction measurements revealed that P4MP1 in the thin film after isothermal crystallization formed a Form I crystal polymorph composed of a tetragonal unit cell with a 72 helix, in which the chain axis was oriented along the direction parallel to the quartz interface. Combining sum-frequency generation vibrational spectroscopy with molecular dynamics simulation enabled us to gain access to the local conformation of P4MP1 chains at the quartz interface and the changes that occurred with isothermal crystallization. Finally, the way in which the initial chain orientation at the substrate interface impacted the crystalline structure in the thin film was discussed.. |
| 83. | Y. Ogata, T. Abe, S. Yonemori, N. L. Yamada, D. Kawaguchi, K. Tanaka, Impact of the Solid Interface on Proton Conductivity in Nafion Thin Films, Langmuir, 10.1021/acs.langmuir.8b03396, 34, 50, 15483-15489, 2018.11, [URL], Proton conductivity of polyelectrolytes in the interfacial region with a solid is key to the performance of polyelectrolyte-based fuel cells. The proton conductivity of Nafion thin films was examined as a function of the thickness along both directions, normal and parallel to the interface. Neutron reflectivity measurements revealed that a water-containing multilamellar structure was formed at the substrate interface. The presence of the interfacial layer, or the two-dimensional proton-conductive pathway, suppressed and enhanced the out-of-plane and in-plane proton conductivities, respectively. The method of proton conductivity in the interfacial region differed from that in the bulk, namely, the Grotthuss mechanism. Using laminated films, we conclude by showing that the proton conductivity in the Nafion thin film changes on the basis of the interface-to-volume ratio. This knowledge will be helpful for the design of devices containing polyelectrolytes with solid materials.. |
| 84. | H. K. Nguyen, M. Inutsuka, D. Kawaguchi, K. Tanaka, Direct Observation of Conformational Relaxation of Polymer Chains at Surfaces, ACS Macro Letters, 10.1021/acsmacrolett.8b00411, 7, 10, 1198-1202, 2018.09, [URL], Sum-frequency generation spectroscopy was employed to follow the conformation evolution of polystyrene chains at the surface of a spin-coated film in a temperature-ramping mode as well as under isothermal annealing. The conformation of surface chains in an as-cast film was observed to be in a nonequilibrium state, in accordance with reported results for polymer chains in thin spin-coated films. While the relaxation of surface nonequilibrium chains was induced by the enhanced surface mobility, the whole chain motion such as reptation might be a key factor in determining the time scale for equilibrating the surface chain conformation.. |
| 85. | H. Kim, D. Kawaguchi, K. Tanaka, Y. Seo, Fracture Mechanism Change at a Heterogeneous Polymer-Polymer Interface Reinforced with in Situ Graft Copolymers, Langmuir, 10.1021/acs.langmuir.8b01860, 34, 37, 11027-11033, 2018.08, [URL], Dynamic secondary-ion mass spectroscopy (DSIMS) was used to investigate the change in the failure mechanism at a heterogeneous polymer-polymer interface (polystyrene (PS)/polyamide (nylon 6, Ny6)) reinforced with in situ graft copolymers produced by the reaction between Ny6 molecules and poly(styrene-co-maleic anhydride) at the interface. The variation in fracture toughness with bonding time and temperature has been explained by two different failure mechanisms: adhesive failure at the interface for short bonding times and when the bonding temperature is low and cohesive failure between chains at the interface and bulk PS for longer bonding times and when the bonding temperature is high. DSIMS results provide the direct experimental evidence that the nonreactive molecules (PS) diffuse away from the high-potential interface, which induces the cohesive failure in the bulk of the nonreactive molecules (PS) after long annealing times. The change in the adhesion strength with temperature could also cause a change in the failure mechanism. Common features of the fracture mechanisms at heterogeneous interfaces reinforced by the in situ graft copolymers are outlined, which are independent of the polymer crystallinity.. |
| 86. | Y. Hong, Y. Li, F. Wang, B. Zuo, X. Wang, L. Zhang, D. Kawaguchi, K. Tanaka, Enhanced Thermal Stability of Polystyrene by Interfacial Noncovalent Interactions, Macromolecules, 10.1021/acs.macromol.8b01012, 51, 15, 5620-5627, 2018.07, [URL], The local conformation of polystyrene (PS) and deuterated PS at the interface with quartz substrates, which were covered with phenyl groups using phenyltrimethoxysilane (PTS) under various conditions, was examined by sum frequency generation spectroscopy. As evidenced by the red-shift of the wavenumber of the v 2 vibration mode for phenyl groups, it was claimed that PTS phenyl groups standing vertically from the quartz surface induced the perpendicular orientation of PS phenyl rings by energetically favorable parallel-displaced π-π interactions at the interface. The local conformation of PS chains strongly anchored onto the substrate by the π-π interactions remained almost unchanged for 48 h even at a temperature 60 K higher than the bulk glass transition temperature. That is, the interfacial π-π interactions facilitated the adsorption of PS chains on the substrate to attain a large enthalpic gain, resulting in significantly slower dynamics of PS chains at the interface. Our results illustrate the importance of the interfacial noncovalent interactions in controlling the structure and dynamics of macromolecular chains at the interface as well as in the thin film geometry.. |
| 87. | Y. Matsumoto, A. Shundo, M. Ohno, N. Tsuruzoe, M. Goto, K. Tanaka, Mesoscopic Heterogeneity in Pore Size of Supramolecular Networks, Langmuir, 10.1021/acs.langmuir.8b00641, 34, 25, 7503-7508, 2018.06, [URL], There has been a considerable interest in developing new types of gels based on a network of fibrous aggregate composed of low molecular weight gelators, also known as supramolecular gels (SMGs). Unlike conventional polymer gels with chemical cross-linking, the network formation in SMGs does not involve any covalent bonds. Thus, the network in SMGs has been often regarded as homogenous or less heterogeneous in comparison with that in chemically cross-linked polymer gels. In this study, we have experimentally verified the existence of the network heterogeneity even in SMGs. The thermal motion of probe particles in SMGs, which were prepared from aqueous dispersions of gelators having a different number of peptide residues, PalGH, PalG2H, and PalG3H, was tracked. The gels were spatially heterogeneous in terms of the network pore size, as evidenced by the variation in the particle motion depending on the location, at which a particle existed. With varying particle size, it was found that the characteristic length scale of the heterogeneity was in the order of (sub)micrometers and was smaller in the order of the PalG2H, PalG3H, and PalGH gels.. |
| 88. | S. Shimomura, H. Matsuno, Y. Kinoshita, S. Fujimura, K. Tanaka, Cellular Behaviors on Polymeric Scaffolds with 2D-patterned Mechanical Properties, Polym. J., 10.1038/s41428-018-0043-9, 50, 8, 737-743, 2018.04, [URL], We propose a novel concept for cellular scaffolds with 2D-patterned mechanical properties. Thin films of glassy polystyrene (PS) with thicknesses ranging from 100 nm to 1 μm were prepared on epoxy resin-based line and space (L&S) patterned substrates. Although the outermost surface of PS on the L- and S-regions was sufficiently flat at the same level, the mechanical responses differed depending on the presence of the underlying resin foundation. The initial cell adhesion and spreading and the proliferation on the scaffolds were affected by the 2D-patterned mechanical properties, that is, cellular behavior was suppressed on mechanically unstable S-regions.. |
| 89. | B. Zuo, M. Inutsuka, D. Kawaguchi, X. Wang, K. Tanaka, Conformational Relaxation of Poly(styrene- co -butadiene) Chains at Substrate Interface in Spin-Coated and Solvent-Cast Films, Macromolecules, 10.1021/acs.macromol.7b02756, 51, 6, 2180-2186, 2018.03, [URL], The local conformation of poly(styrene-co-butadiene) rubber (SBR) chains in direct contact with a quartz substrate was examined by interface-sensitive sum-frequency generation (SFG) spectroscopy. SFG signals, which could be obtained from functional groups only oriented at the interface, were clearly observed for SBR in a film at room temperature which was much higher than the bulk glass transition temperature (Tg). When the film was thermally annealed, SBR chains at the quartz interface changed their conformation to one with a lower energy state, accompanied by the randomization of both the main and side chain parts. The characteristic temperature, at which interfacial chains started to lose their orientations, was much higher than the bulk Tg. Also, the extent found to be more remarkable for the spin-coated film than for the solvent-cast one. This implies that the stress accumulated at the interface, which resulted from the centrifugal force during the spin-coating process, accelerates the mobility of chains there. Finally, the kinetics experiment well supports the slower orientation relaxation at the interface.. |
| 90. | K. Tanaka, K. Shimakawa, Mechanisms of Photoinduced Fluidity in Chalcogenide Glasses: Molecular Orbital Analyses, Journal OF Non-Crystalline Solids, 10.1016/j.jnoncrysol.2017.12.005, 481, 579-584, 2018.02, Atomic processes giving rise to the photoinduced fluidity have been studied for amorphous selenium. Ab initio molecular orbital calculations of Se clusters suggest that distorted atomic structures such as curled and intersecting chains have smaller optical gaps. Those atomic sites are likely to be excited by subgap (Urbach-edge) light, which undergo structural relaxation including bond breakages and interchanges. Such photo-electro-structural transformations could originate the macroscopic fluidity. Possibility of electronic glass-transition is also discussed.. |
| 91. | H. Matsuno, S. Irie, T. Hirata, R. Matsuyama, Y. Oda, H. Masunaga, Y. Seki, S. Aoshima, K. Tanaka, Heterogeneous Adhesion of Cells on Polymer Surfaces with Underlying Amorphous/Crystalline Phases, Journal of Materials Chemistry B, 10.1039/c7tb03250a, 6, 6, 903-907, 2018.01, [URL], Fibroblastic adhesion behaviour on films of a poly[(2-methoxyethyl vinyl ether) (PMOVE)-block-(l-lactic acid) (PLLA)], in which the surface was covered with PMOVE, was studied. Fibroblasts were sufficiently sensitive to identify crystalline/non-crystalline regions existing beneath the surface PMOVE layer.. |
| 92. | M. Sen, N. Jiang, M. K. Endoh, T. Koga, A. Ribbe, A. Rahman, D. Kawaguchi, K. Tanaka, D. M. Smilgies, Locally Favored Two-Dimensional Structures of Block Copolymer Melts on Nonneutral Surfaces, Macromolecules, 10.1021/acs.macromol.7b02506, 51, 2, 520-528, 2018.01, [URL], Self-assembly of block copolymers (BCPs) into arrays of well-defined nanoscopic structures has attracted extensive academic and industrial interests over the past several decades. In contrast to the bulk where phase behavior is controlled by the segmental interaction parameter, the total number of segments in BCPs and volume fraction, the morphologies and orientations of BCP thin films can also be strongly influenced by the substrate surface energy/chemistry effect (considered as a "substrate field"). Here, we report the formation of locally favored structures where all constituent blocks coexist side-by-side on nonneutral solid surfaces irrespective of their chain architectures, microdomain structures, and interfacial energetics. The experimental results using a suite of surface-sensitive techniques intriguingly demonstrate that individual preferred blocks and nonpreferred blocks lie flat on the substrate surface and form a two-dimensional percolating network structure as a whole. The large numbers of solid-segment contacts, which overcome a loss in the conformational entropy of the polymer chains, prevent the structure relaxing to its equilibrium state (i.e., forming microdomain structures) even in a (good) solvent atmosphere. Our results provide direct experimental evidence of the long-lived, nonequilibrium structures of BCPs and may point to a new perspective on the self-assembly of BCP melts in contact with impenetrable solids.. |
| 93. | S. Sugimoto, M. Inutsuka, D. Kawaguchi, K. Tanaka, Reorientation Kinetics of Local Conformation of Polyisoprene at Substrate Interface, ACS Macro Letters, 10.1021/acsmacrolett.7b00927, 7, 1, 85-89, 2018.01, [URL], The performance of a polymer composite material, in which inorganic fillers are dispersed, is closely related to the aggregation states and dynamics of polymer chains at the interface with the filler. In this study, the local conformation of polyisoprene (PI) at a quartz substrate interface was studied as a model system for the rubber/filler composite material. PI films were prepared from a toluene solution onto quartz substrates by a spin-coating method. Sum-frequency generation spectroscopy revealed that the local conformation of PI chains at the quartz interface depended on the spinning rate. The tilt angle of methyl groups increased with the rotational speed, probably due to the centrifugal force applied to chains and probably also the evaporation rate of the solvent during the solidification process. This result indicates that the interfacial orientation of PI chains can remain even at room temperature, which is 87 K higher than the bulk glass transition temperature (Tg b). The interfacial orientation disappeared at a temperature approximately 120 K higher than Tg b.. |
| 94. | A. Shundo, T. Yamamoto, Y. Tezuka, K. Tanaka, Load-Induced Frictional Transition for Well-Defined Cyclic Self-Assembled Monolayers, Toraibarojisuto/Journal of Japanese Society of Tribologists, 63, 4, 248-252, 2018.01, Self-Assembled monolayer (SAM) with amphiphilic linear molecules has been studied as a surface modifier. In general, the surface properties of a SAM are dependent on the chain end chemistry of the molecules. Thus, a SAM composed of alkane loops from cyclic alkanedisulfide on a gold substrate, in which both sulfurs arc bound to gold, may possess unique surface properties due to the chain folding as well as a lack of chain ends. We here focus on the frictional properties of the linear and cyclic SAMs. For the cyclic SAM, the load dependence of the frictional force became more striking beyond a threshold. Such a frictional transition was not observed for the corresponding linear SAM. The load-induced transition in the frictional response from the alkane loops could be related to the conformational change of the alkane loops, which collapsed along the direction normal to the SAM surface.. |
| 95. | K. Tanaka, Aggregation States and Thermal Molecular Motion of Polymer Chains at Solid Interfaces, Journal of Fiber Science and Technology, .org/10.2115/fiber.74.P-6, 74, 1, 6-9, 2018.01. |
| 96. | N. Itagaki, Y. Oda, T. Hirata, H. K. Nguyen, D. Kawaguchi, H. Matsuno, K. Tanaka, Surface Characterization and Platelet Adhesion on Thin Hydrogel Films of Poly(vinyl ether), Langmuir , 10.1021/acs.langmuir.7b03427, 33, 50, 14332-14339, 2017.12, Poly(vinyl ether), with short oxyethylene side chains which possess a simple and relatively polar structure, should be a unique candidate for a bioinert material thanks to its solubility in water. On the basis of living cationic copolymerization and subsequent ultraviolet light irradiation, thin films of poly(2-methoxyethyl vinyl ether) with different cross-linking densities were prepared on solid substrates. The films were thickened in water, and the extent was dependent on the cross-linking density. Although the surface chemistry and aggregation states were almost identical to one another, the stiffness, or the softness, of the outermost region in the film was strongly dependent on the cross-linking density. That is, the interface between polymer and water became thicker, or more diffused, with decreasing cross-linking density. The blood compatibility based on the platelet adhesion on to the hydrogel films was better for a more diffused interface.. |
| 97. | D. A. Barkley, N. Jiang, M. Sen, M. K. Endoh, J. G. Rudick, T. Koga, Y. Zhang, O. Gang, G. Yuan, S. K. Satija, D. Kawaguchi, K. Tanaka, A. Karim, Chain Conformation Near the Buried Interface in Nanoparticle-Stabilized Polymer Thin Films, Macromolecules, 10.1021/acs.macromol.7b01187, 50, 19, 7657-7665, 2017.10, [URL], It is known that when nanoparticles are added to polymer thin films, they often migrate to the film-substrate interface and form an "immobile interfacial layer", which is believed to be the mechanism behind dewetting suppression. We here report a new mechanism of dewetting suppression from the structural aspect of polymer chains accommodated at the film-substrate interface. Dodecanethiol-functionalized gold (Au) nanoparticles embedded in relatively low molecular weight PS thin films prepared on silicon (Si) substrates were used as a model. We mimicked the previously reported conditions, where the nanoparticles preferentially migrate to the substrate, and successfully stabilized the PS thin films via thermal annealing. A suite of surface-sensitive techniques including atomic force microscopy, grazing incidence small-angle X-ray scattering, X-ray/neutron reflectivity, and sum frequency generation spectroscopy in conjunction with the established solvent leaching process enabled us to unveil the polymer chain conformation and the dispersion structure of the nanoparticles at the film-substrate interface. The results evidenced that thermal annealing promotes irreversible polymer adsorption onto the substrate surface along with the migration of the nanoparticles. In addition, we found that the migration of the nanoparticles causes the changes in the conformations and interfacial orientations of the adsorbed polymer chains compared to those of the adsorbed polymer chains formed in the nanoparticle-free PS thin film. The resultant interfacial polymer structure allows for the interpenetration between free chains and the adsorbed chains, thereby stabilizing the thin film.. |
| 98. | K. Tanaka, A Polaronic View of Impact Ionization in Amorphous Se Films, Physica Status Solidi-Rapid Research Letters, 10.1002/pssr.201700254, 11, 10, 2017.10, In this letter, it is proposed that the impact ionization in amorphous Se films, which triggers avalanche carrier multiplications, occurs through transformations of electron and hole motions from polaronic to supersonic states, the situation resembling those envisaged for semiconducting one-dimensional organic polymers. However, reflecting unique origins of the conduction and the valence band in Se, the electron-lattice interaction appears stronger than the hole-lattice interaction, which seems to be responsible for characteristic properties such as less efficient electron multiplication. The idea is consistent with the fact that a-Si:H having three-dimensional structures exhibits no corresponding phenomena.. |
| 99. | Y. Matsumoto, A. Shundo, M. Ohno, N. Tsuruzoe, M. Goto, K. Tanaka, Evolution of Heterogeneity Accompanying Sol-Gel Transitions in a Supramolecular Hydrogel, Soft Matter, 10.1039/c7sm01612c, 13, 40, 7433-7440, 2017.10, When a peptide amphiphile is dispersed in water, it self-assembles into a fibrous network, leading to a supramolecular hydrogel. When the gel is physically disrupted by shaking, it transforms into a sol state. After aging at room temperature for a while, it spontaneously returns to the gel state, called sol-gel transition. However, repeating the sol-gel transition often causes a change in the rheological properties of the gel. To gain a better understanding of the sol-gel transition and its reversibility, we herein examined the thermal motion of probe particles at different locations in a supramolecular hydrogel. The sol obtained by shaking the gel was heterogeneous in terms of the rheological properties and the extent decreased with increasing aging time. This time course of heterogeneity, or homogeneity, which corresponded to the sol-to-gel transition, was observed for the 1st cycle. However, this was not the case for the 2nd and 3rd cycles; the heterogeneity was preserved even after aging. Fourier-transform infrared spectroscopy, small-angle X-ray scattering, and atomic force and confocal laser scanning microscopies revealed that, although the molecular aggregation states of amphiphiles both in the gel and sol remained unchanged with the cycles, the fibril density diversified to high and low density regions even after aging. The tracking of particles with different sizes indicated that the partial mesh size in the high density region and the characteristic length scale of the density fluctuation were smaller than 50 nm and 6 mm, respectively.. |
| 100. | H. K. Nguyen, A. Konomi, S. Sugimoto, M. Inutsuka, D. Kawaguchi, K. Tanaka, Rotational Dynamics of a Probe in Rubbery Polymers Characterized by Time-Resolved Fluorescence Anisotropy Measurement, Macromolecular Chemistry and Physics, 10.1002/macp.201700329, 219, 3, 2017.09, [URL], The rotational relaxation time (τrot) of a fluorescent molecule, coumarin 153 (C153), dispersed in different rubbery polymers is characterized by time-resolved fluorescence anisotropy measurement, and an attempt is made to quantitatively combine it with the segmental relaxation time (τseg) of the corresponding matrix polymer obtained by dielectric relaxation spectroscopy. This study here demonstrates that τseg extrapolated to higher temperatures using the Vogel–Fulcher–Tammann law can be superimposed on τrot, resulting in a single curve. This behavior is common for polymers with different glass transition temperatures such as polyisoprene and acrylonitrile/butadiene copolymer, implying that the rotational dynamics of C153 is a useful tool for the characterization of polymer dynamics.. |
| 101. | H. Taneda, A. Shundo, H. Matsuno, K. Tanaka, Design of a Well-Defined Polyrotaxane Structure on a Glassy Polymer Surface, Langmuir, 10.1021/acs.langmuir.7b03130, 34, 2, 709-714, 2017.09, [URL], 水界面における高分子鎖のダイナミクスは、生体関連機能の発現において重要な役割を果たすと考えられている。したがって、分子鎖ダイナミクスの制御のための一つの戦略は、ポリマー鎖を環状化合物で包接し、複合体を形成することであるが、そのような検討はこれまでバルク試料に限られていた。本研究では、典型的なガラス状高分子であるポリメタクリル酸メチルの膜を調製し、クリック反応とLangmuir-Blodgett法を組み合わせることで、膜最表面にポリ（エチレンオキシド）（PEO）と-シクロデキストリン（CD）からなるポリロタキサン構造を導入することに成功している。また、水界面でのPEOの熱運動が、CD分子の導入によって抑制され、その結果、タンパク質吸着や血小板接着のような生物学的応答が変化することを始めて示している。. |
| 102. | K. Yamamoto, T. Hirai, Y. Oda, D. Kawaguchi, H. Matsuno, K. Tanaka, A Polymer Interfacial Modifier Synthesized by Living Anionic Polymerization Incorporation of Inorganic Blocks to Chain Ends, Macromolecular Chemistry and Physics, 10.1002/macp.201600473, 218, 12, 2017.06, [URL], As a polymer interfacial modifier, poly(methyl methacrylate) (PMMA) terminated with elemental blocks of polyhedral oligomeric silsesquioxane (POSS) has been exploited through the phenomenon of preferential segregation in PMMA films. The modifier synthesized by living anionic polymerization using a bifunctional initiator is segregated at the surface in the mixture of PMMA due to a “buoy” effect of the POSS blocks. This further results in the surface wettability of PMMA being regulated on the basis of the amount of the modifier fed into the matrix. Finally, it is shown that the amount of the modifier in the PMMA films affects the cell proliferation behavior via the wettability. (Figure presented.).. |
| 103. | H. K. Nguyen, M. Inutsuka, D. Kawaguchi, K. Tanaka, Depth-Resolved Local Conformation and Thermal Relaxation of Polystyrene Near Substrate Interface, Journal of Chemical Physics, 10.1063/1.4976523, 146, 20, 2017.05, [URL], By means of sum-frequency generation spectroscopy, we report a depth-resolved measurement of the local conformation and chain relaxation of polystyrene (hPS) located at different distances from the quartz interface. To control the distance from the quartz interface, deuterated polystyrene (dPS) layers with thicknesses of 3.4, 7.5, and 20 nm were coated on the quartz substrates. The hPS chains in direct contact with the substrate surface predominantly orient their phenyl rings in a direction normal to the substrate. This conformation was found to be barely relaxed when the film was annealed for 24 h at 423 K, higher than the bulk glass transition temperature. In contrast, for the hPS chains supported on the dPS layer, the orientation of phenyl rings of hPS became weaker with the annealing and this trend was more significant with increasing distance from the quartz substrate. In particular, the orientation of phenyl rings of hPS after annealing vanished at a distance of 20 nm. These results might provide an important evidence of the difference in the relaxation dynamics of the PS chains located at different distances from the quartz interface.. |
| 104. | H. Matsuno, R. Tsukamoto, Y. Oda, K. Tanaka, Platelet Adhesion on the Surface of a Simple Poly(vinyl ether), Polymer, 10.1016/j.polymer.2017.01.036, 116, 479-486, 2017.05, A better understanding of controlling factors in the control of bio-events on polymer surfaces is the first benchmark toward realization of life innovation. Although it has been accepted that a family of poly(vinyl ether) (PVE) with various side chain structures is a good candidate for a blood compatible material, the reasons are not fully understood. In this study, poly(vinyl ether) with a simple side chain structure, poly(ethyl vinyl ether) (PEVE), was studied. Since the glass transition temperature of PEVE is lower than room temperature, its thin films can be difficult to prepare. Thus, PEVE was mixed with a glassy polymer of poly(p-vinylphenol) (PVPh). The aggregation states of polymer chains and water molecules at the interface were characterized by the interfacial sensitive spectroscopy. The relationship between the structural information and the platelet adhesion behavior is discussed. This leads to a hypothesis that the states of water molecules affect platelet adhesion and activation behaviors on PVE. (C) 2017 Elsevier Ltd. All rights reserved.. |
| 105. | K. Tanaka, Structure, Physical Properties and Function of Polymers at Various Interfaces, 繊維学会誌, 73, 5, 207-207, 2017.05. |
| 106. | T. Ono, K. Kawasaki, K. Tanaka, T. Nagamura, Ultrafast Photoresponsive Materials for All-optical Light Modulation by Polymer Thin Films, Polymer, 10.1016/j.polymer.2017.02.051, 116, 523-533, 2017.05, Ultrafast and single exponential responsive materials were achieved by encapsulating donor-acceptor linked molecules into cucurbitunitl[8], CB[8], as nanocavity hosts. Various aromatic groups were linked with various types of 4,4'-bipyridinium groups through propyloxy linker. They showed characteristic charge-transfer (CT) absorption with specific colors in aqueous solutions. Upon addition of CB[8], they showed remarkably different colors due to intramolecular CT complex formation in CB[8]. Upon femtosecond laser excitation of CT band extremely fast electron transfer occurred from a donor to an acceptor unit accompanying new absorption in the visible to near-infrared region due mainly to photoreduced bipyridinium derivatives. Thermal back electron transfer reactions in CB[8] were found to follow a single exponential decay with rate constants ranging more than two orders depending on the combination of a donor and an acceptor unit. Their rate constants vs. free energy changes for oxidized donors and reduced acceptors in linked molecules were expressed by the Marcus theory. (C) 2017 Elsevier Ltd. All rights reserved.. |
| 107. | S. Shimomura, H. Matsuno, K. Sanada, K. Tanaka, Cell Adhesion on Glassy Scaffolds with a Different Mechanical Response, Journal of Materials Chemistry B, 10.1039/c6tb02617f, 5, 4, 714-719, 2017.03. |
| 108. | B. Zuo, Y. Liu, Y. Liang, D. Kawaguchi, K. Tanaka, X. Wang, Glass Transition Behavior in Thin Polymer Films Covered with a Surface Crystalline Layer, Macromolecules, 10.1021/acs.macromo1.6b02740, 50, 5, 2061-2068, 2017.03. |
| 109. | A. Shundo, K. Hori, Y. Tezuka, T. Yamamoto, K. Tanaka, Load-Induced Frictional Transition at a Well-Defined Alkane Loop Surface, Langmuir, 10.1021/acs.langmuir.6b04042, 33, 9, 2396-2401, 2017.03, 自己組織化単分子膜（SAM）は、材料表面に望みの物性・機能性を与えるための分子ツールとして注目され、実デバイスなどにも広く用いられてきた。しかしながら、これまで、SAM形成は線状分子に限定されており、表面物性・機能性への分子末端の影響が避けられないなどの問題があった。しかしながら、本研究では、環状アルカンジスルフィドを用いることで炭化水素環状鎖からなるSAMを形成することに成功し、表面物性・機能性への分子末端の影響を明確にしている。この結果は、材料表面の物性・機能性設計へ新たな指針を提案するものとして高く評価されている。. |
| 110. | T. Iizuka, Y. Ohtake, K. Tanaka, A Synergistic Effect of Light and Heat on Degradation for Polypropylene, Zairyo/Journal of the Society of Materials Science, Japan, 10.2472/jsms.66.238, 66, 3, 238-243, 2017.03, [URL], Oxidative degradation of polypropylene (PP) is accelerated by not only sunlight but also temperature. Here we propose how the degradation behavior of PP under ultraviolet light irradiation conditions at elevated temperatures, which are more severe than the standards set by the Japanese Industrial Standards (JIS), can be examined. Fourier-transform infrared spectroscopy in conjunction with gel permeation chromatography revealed that the combination of light and heat definitely accelerated the chain scission, or oxidative degradation, of PP, resulting in deterioration of mechanical properties for PP.. |
| 111. | T. Hirata, H. Matsuno, D. Kawaguchi, M. Inutsuka, T. Hirai, M. Tanaka, K. Tanaka, Dynamics of a Bioinert Polymer in Hydrated States by Dielectric Relaxation Spectroscopy, Physical Chemistry Chemical Physics, 10.1039/c6cp07322k, 19, 2, 1389-1394, 2017.01, The chain dynamics of well-defined poly(2-methoxyethyl acrylate) (PMEA), which has been used in practice as a bioinert coating for heart-lung machines, was examined as a function of water content by dielectric relaxation spectroscopy (DRS). Two relaxation processes observed in both dried and hydrated films were assigned to the segmental motion (alpha-process) and the relatively smaller scale motion such as the hindered rotation of side chains (beta-process). Water molecules adsorbed on PMEA made the alpha-process faster, meaning that water molecules in PMEA played the role of a plasticizer. Combining the above knowledge with the depth dependence of water content in the PMEA film previously obtained by neutron reflectivity, the segmental dynamics of PMEA at the water interface, which should be crucial to bio-inertness, is discussed. We found that the segmental motion was markedly faster than that in the bulk and almost comparable to the side chain motion.. |
| 112. | S. Sugimoto, Y. Oda, T. Hirata, R. Matsuyama, H. Matsuno, K. Tanaka, Surface Segregation of a Branched Polymer with Hydrophilic Poly[2-(2-ethoxy)ethoxyethyl vinyl ether] Side Chains, Polymer Chemistry, 10.1039/c6py01984f, 8, 3, 505-510, 2017.01, A poly[2-(2-ethoxy) ethoxyethyl vinyl ether] macromonomer with a terminal vinyl group synthesized by living cationic polymerization was successively copolymerized with methyl methacrylate by atom transfer radical polymerization. The branched polymer mixed into poly(methyl methacrylate) was preferentially segregated at the film surface, leading to an anti-biofouling polymer surface.. |
| 113. | C-C. Shih, C-Y. Chung, H-C. Wu, Y. Morimitsu, H. Matsuno, K. Tanaka, W-C. Chen, Transparent Deoxyribonucleic Acid Substrate with High Mechanical Strength for Flexible and Biocompatible Organic Resistive Memory Devices, Chem. Comm., 10.1039/c6cc07648c, 52, 92, 13463-13466, 2016.11. |
| 114. | Y. Morimitsu, H. Matsuno, N. Ohta, H. Sekiguchi, K. Tanaka, Direct Correlation between Molecular Cross-linking and Macroscopic Mechanical Properties for Green Solids of Deoxyribonucleic Acids, Chem Nano Mat, 10.1002/cnma.201600222, 2, 11, 1023-1027, 2016.11. |
| 115. | T. Iizuka, Y. Ohtake, K. Tanaka, A Effect of Moisture on Photo-Degradation for Polypropylene, Zairyo/Journal of the Society of Materials Science, Japan, 10.2472/jsms.65.812, 65, 11, 812-817, 2016.11, Photo-degradation of polymers for outdoor use are accelerated by degradation factors such as heat and moisture. Polypropylene(PP) is excellent in water resistance, but is inferior to weatherability. Therefore, in this study, PP was exposed under the water spray condition by using Xenon arc lamp. We evaluated the synergistic effect of light and moisture using the quantification technique of degradation. Results from the Fourier-transform infrared spectroscopic and X-ray Photoelectron Spectroscopy revealed that moisture accelerated the oxidative degradation of PP. In addition, with the progress of the oxidative degradation, melting point and thermal decomposition temperature of PP was lowered. The resulting collapse of crystal structure and chain scission therefore deteriorated the mechanical properties (Charpy impact strength, elongation) of PP.. |
| 116. | S. Shimomura, M. Inutsuka, N. L. Yamada, K. Tanaka, Unswollen Layer of Cross-Linked Polyisoprene at the Solid Interface, Polymer, 10.1016/j.polymer.2016.07.047, 105, 526-531, 2016.11, The density profile in a thin cross-linked polyisoprene (PI) film spin-coated on a quartz substrate in n-hexane was examined by specular neutron reflectivity. We found two layers with different PI densities at the substrate interface. The characteristics of the layers are discussed in terms of bound rubber typically associated with the field of rubber materials and adsorbed layers typically associated with the field of glassy materials. (C) 2016 Elsevier Ltd. All rights reserved.. |
| 117. | S. Shimomura, M. Inutsuka, K. Tajima, M. Nabika, S. Moritomi, H. Matsuno, K. Tanaka, Stabilization of Polystyrene Thin Films by Introduction of a Functional End Group, Polym. J., 10.1038/pj.2016.58, 48, 9, 949-953, 2016.09. |
| 118. | H. Matsuno, R. Tsukamoto, Y. Kaneshiro, S. Yamada, K. Tanaka, Platelet Adhesion on Films of Poly(vinylene carbonate) and Its Derivatives, Chemistry Letters, 10.1246/cl.160373, 45, 8, 913-915, 2016.08. |
| 119. | A. Shundo, K. Hori, P. D. Penaloza Jr, Y. Matsumoto, Y. Okumura, H. Kikuchi, K. E. Lee, S. O. Kim, K. Tanaka, Hierarchical Spatial Heterogeneity in Liquid Crystals Composed of Graphene Oxides, Physical Chemistry Chemical Physics, 10.1039/c6cp03614g, 18, 32, 22399-22406, 2016.08. |
| 120. | K. Okamoto, T. Ganbe, N. Sekine, M. Aoki, M. Inutsuka, A. Shundo, D. Kawaguchi, K. Tanaka, Nanoscale Characterization of Epoxy Interface on Silica, 1st IEEE International Conference on Dielectrics, ICD 2016 Proceedings of the 2016 IEEE International Conference on Dielectrics, ICD 2016, 10.1109/ICD.2016.7547549, 1, 84-87, 2016.08, [URL], The objective of this study is to carry out nanoscale characterization of the epoxy resin interface on silica by determining the glass-transition temperature (Tg) and molecular conformation at the interface by means of a novel non-destructive method. The Tg was determined by fluorescence lifetime measurements using evanescent wave excitation. It was revealed that the Tg of epoxy resin at a distance of 30 nm from the interface was 10 K higher than that at a distance of 80 nm. The chemical composition and molecular conformation were analysed by X-ray photoelectron spectroscopy and sum-frequency generation (SFG) spectroscopy, respectively. The SFG data revealed that unreacted epoxy group remained at the interface. The Tg of epoxy resin increased in the regions near the interface, and the epoxy group remained unreacted at a distance of ca. 10 nm or less from the interface.. |
| 121. | Y. Oda, C. Zhang, D. Kawaguchi, H. Matsuno, S. Kanaoka, S. Aoshima, K. Tanaka, Design of Blood-Compatible Interfaces with Poly(vinyl ether)s, Advanced Materials Interfaces, 10.1002/admi.201600034, 3, 12, 2016.06. |
| 122. | Y. Oda, C. Zhang, D. Kawaguchi, H. Matsuno, S. Kanaoka, S. Aoshima, K. Tanaka, Bio-Inert Surfaces: Design of Blood-Compatible Interfaces with Poly(vinyl ether)s (Adv. Mater. Interfaces 12/2016), Advanced Materials Interfaces, 10.1002/admi.201670058, 3, 12, 2016.06, [URL]. |
| 123. | M. Sen, N. Jiang, J. Cheung, M. K. Endoh, T. Koga, D. Kawaguchi, K. Tanaka, Flattening Process of Polymer Chains Irreversibly Adsorbed on a Solid, ACS Macro Letters, 10.1021/acsmacrolett.6b00169, 5, 4, 504-508, 2016.04. |
| 124. | S. Shimomura, H. Matsuno, T. Ohta, S. Kawahara, K. Tanaka, Initial Adhesion of Fibroblasts on Thin Rubber Scaffolds, Chemistry Letters, 10.1246/cl.160061, 45, 4, 475-477, 2016.04. |
| 125. | H. Matsuno, R. Tsukamoto, S. Shimomura, T. Hirai, Y. Oda, K. Tanaka, Platelet-adhesion Behavior Synchronized with Surface Rearrangement in a Film of Poly(methyl methacrylate) Terminated with Elemental Blocks, Polym. J., 10.1038/pj.2015.118, 48, 4, 413-419, 2016.04. |
| 126. | K. Tanaka, T. Serizawa, W-C. Chen, K. Char, T. Kato, Special Issue: Polymer Surfaces, Interfaces and Thin Films, Polym. J., 10.1038/pj.2016.26, 48, 4, 323-323, 2016.04. |
| 127. | T. Sagawa, F. Ito, A. Sakai, Y. Ogata, K. Tanaka, H. Ikeda, Substituent-dependent Backward Reaction in Mechanofluorochromism of Dibenzoylmethanatoboron Difluoride Derivatives, Photochemical & Photobiological Sciences, 10.1039/c5pp00453e, 15, 3, 420-430, 2016.03. |
| 128. | Y. Ogata, D. Kawaguchi, K. Tanaka, The Impact of Polymer Dynamics on Photoinduced Carrier Formation in Films of Semiconducting Polymers, Journal of Physical Chemistry Letters, 10.1021/acs.jpclett.5b02255, 6, 23, 4794-4798, 2015.12. |
| 129. | T. Hirata, H. Matsuno, D. Kawaguchi, N. L. Yamada, M. Tanaka, K. Tanaka, Construction of a Blood-compatible Interface Based on Surface Segregation in a Polymer Blend, Polymer, 10.1016/j.polymer.2015.10.001, 78, 219-224, 2015.11. |
| 130. | M. Watanabe, H. Hagiwara, Y. Ogata, A. T. Staykov, S. R. Bishop, N. H. Perry, Y. J. Chang, S. Ida, K. Tanaka, T. Ishihara, Impact of Alkoxy Chain Length on Carbazole-Based, Visible Light-Driven, Dye Sensitized Photocatalytic Hydrogen Production, Journal of Materials Chemistry A, 10.1039/c5ta04991a, 3, 43, 21713-21721, 2015.11. |
| 131. | K. Matsumoto, A. Shundo, M. Ohno, K. Saruhashi, N. Miyachi, N. Tsuruzoe, K. Tanaka, Sol-gel Transition Accelerated by The Co-assembly of Two Components in Supramolecular Hydrogels, Physical Chemistry Chemical Physics, 10.1039/c5cp04800a, 17, 40, 26724-26730, 2015.10. |
| 132. | M. Inutsuka, A. Horinouchi, K. Tanaka, Aggregation States of Polymers at Hydrophobic and Hydrophilic Solid Interfaces, ACS Macro Letters, 10.1021/acsmacrolett.5b00592, 4, 10, 1174-1178, 2015.10. |
| 133. | F. Chen, D. Peng, Y. Ogata, K. Tanaka, Z. Yang, Y. Fujii, N. L. Yamada, C.-H. Lam, O. K. C. Tsui, Confinement Effect on the Effective Viscosity of Plasticized Polymer Films, Macromolecules, 10.1021/acs.macromol.5b01780, 48, 20, 7719-7726, 2015.10. |
| 134. | T. Kajiyama, H. Yakabe, D. Kawaguchi, A. Takahara, K. Tanaka, Melting Behavior of Thin Polyethylene Films, Journal of Plastic Film & Sheeting, 10.1177/8756087915594418, 31, 4, 401-413, 2015.10, Melting behavior in thin films of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) was studied by local thermal analysis (mu TA). Even in the films thinner than 100nm, the melting temperature (T-m) was successfully observed by mu TA. For LLDPE, T-m decreased as the thickness became thinner than 150nm. For HDPE, T-m increased with decreasing thickness. Polarized infrared spectroscopy revealed that an edge-on lamellar structure formed in both cases, meaning that the crystallite orientation may not be a reason why the thickness dependence of T-m was not the same for both resins. A possible explanation is that for LLDPE the segmental mobility in the amorphous region predominates with decreasing thickness, and for HDPE the chain orientation in the region predominates with decreasing thickness.. |
| 135. | H. Lee, S. Jo, T. Hirata, N. L. Yamada, K. Tanaka, E. Kim, D. Y. Ryu, Interpenetration of Chemically Identical Polymer onto Grafted Substrates, Polymer, 10.1016/j.polymer.2015.07.054, 74, 70-75, 2015.09. |
| 136. | T. Hirai, Y. Oda, D. P. Penaloza, D. Kawaguchi, K. Tanaka, Control of Surface Structure and Dynamics of Polymers Based on Precision Synthesis, Anionic Polymerization Principles, Practice, Strength, Consequences and Applications, 10.1007/978-4-431-54186-8_19, 861-880, 2015.09, [URL], Aggregation states and dynamics of polymers at the surface are generally different from those in the corresponding bulk state. To what extent they differ from that of the bulk strongly depends on the polymer primary structure. Therefore, finetuning the surface properties of polymers can be achieved by exhibiting control over their structure using precision polymer synthesis. We here show how the polymer design effectively impacts the structure and dynamics at the surfaces.. |
| 137. | T. Hirata, H. Matsuno, D. Kawaguchi, N. L. Yamada, M. Tanaka, K. Tanaka, Effect of Interfacial Structure on Bioinert Properties of Poly(2-methoxyethyl acrylate)/poly(methyl methacrylate) Blend Films in Water, Physical Chemistry Chemical Physics, 10.1039/c5cp01972a, 17, 26, 17399-17405, 2015.07. |
| 138. | H. Matsuno, R. Matsuyama, A. Yamamoto, K. Tanaka, Enhanced Cellular Affinity for Poly(lactic acid) Surfaces Modified with Titanium Oxide, Polym. J., 10.1038/pj.2015.30, 47, 7, 505-512, 2015.07. |
| 139. | 森賀俊典, 青山直揮, 田中敬二, ウレタンガスケットのシーリング特性に及ぼすR値（NCO基/ OHモル比）の影響, 日本ゴム協会誌, 88, 7, 257-262, 2015.07. |
| 140. | K. Tanaka, K. Kojio, The 45th Summer Seminar - For Realization of Sustainable Society by Time- and Space-Domain Controls of Fibers -, 繊維学会誌, 71, 6, 267-267, 2015.06. |
| 141. | T. Moriga, N. Aoyama, K. Tanaka, Development of a Polyurethane Sealing Gasket with Excellent Sealing and Opening Properties, Polym. J., 10.1038/pj.2015.6, 47, 5, 400-407, 2015.05. |
| 142. | M. Aoki, D. Kawaguchi, T. Ganbe, N. Sekine, K. Okamoto, K. Tanaka, Glass-transition Temperature Determination for Polymers Using Europium Complex as a Fluorescence Probe, Chemistry Letters, 10.1246/cl.150013, 44, 5, 659-661, 2015.05. |
| 143. | D. H. Kim, K. Tanaka, J. Peng, A Special Issue on Functional Polymeric Nanomaterials, Science of Advanced Materials, 10.1166/sam.2015.2274, 7, 5, 827-829, 2015.05, [URL]. |
| 144. | Y. Ogata, D. Kawaguchi, K. Tanaka, An Effect of Molecular Motion on Carrier Formation in a Poly(3-hexylthiophene) Film, Scientific Reports, 10.1038/srep08436, 5, 8436, 2015.04, 本論文は、ポリ（３-ヘキシルチオフェン）（P3HT）膜の光電荷生成と分子運動について検討したものである。 P3HT 膜に光照射すると、正電荷と負電荷との対が形成された後、自発的に正および負電荷に分離されることを見出した。また、この電荷生成の速度定数は、低温では一定であるが、主鎖のねじれ運動に対応する緩和温度から 温度とともに増加した。 このことから、P3HT膜において分子運動は光電荷生成を支配する因子のひとつであると結論した。. |
| 145. | Y. Oda, D. Kawaguchi, T. Hirata, N. L. Yamada, S. Kanaoka, S. Aoshima, K. Tanaka, Density Profiles of Well-defined Poly(methyl 2-propenyl ether) (PMPE) Near Water Interface, Macromolecular Symposia, 350, 1, 99-104, 2015.04. |
| 146. | T. Hirata, H. Matsuno, D. Kawaguchi, T. Hirai, N. L. Yamada, M. Tanaka, K. Tanaka, Effect of Local Chain Dynamics on a Bioinert Interface, Langmuir, 10.1021/acs.langmuir.5b00258, 31, 12, 3661-3667, 2015.03. |
| 147. | S. J. HYUN, S. Dong, K. Röemhild, A. Kaya, D. Sohn, K. Tanaka, M. Roman, T. Heinze, A. R. Esker, 2-Hydroxypropyltrimethylammonium xylan adsorption onto rod-like cellulose nanocrystal, Journal of Colloid and Interface Science, 10.1016/j.jcis.2014.10.071, 440, 119-125, 2015.02. |
| 148. | C. Zhang, Y. Oda, D. Kawaguchi, S. Kanaoka, S. Aoshima, K. Tanaka, Dynamic-driven Surface Segregation of a Hydrophilic Component in Diblock Copolymer Films, Chemistry Letters, 10.1246/cl.140924, 44, 2, 166-168, 2015.02. |
| 149. | D. Kawaguchi, Y. Tateishi, K. Tanaka, Time-Resolved Fluorescence Analysis for Dye-Labeled Polystyrene in Thin Films, Journal of Non-Crystalline Solids, 10.1016/j.jnoncrysol.2014.09.010, 407, 284-287, 2015.01. |
| 150. | K. Matsumoto, A. Shundo, M. Ohno, S. Fujita, K. Saruhashi, N. Miyachi, K. Miyaji, K. Tanaka, Modulation of Physical Properties of Supramolecular Hydrogels Based on a Hydrophobic Core, Physical Chemistry Chemical Physics, 10.1039/c4cp04395b, 17, 3, 2192-2198, 2015.01. |
| 151. | H. Matsuno, T. Ohta, A. Shundo, Y. Fukunaga, K. Tanaka, Simple Surface Treatment of Cell-Culture Scaffolds with Ultrafine Bubble Water, Langmuir, 10.1021/la5035883, 30, 50, 15238-15243, 2014.12, We propose a novel method to treat polymeric scaffold surfaces for cell culture with water containing nanobubbles, called ultrafine bubbles (UFBs), with typical diameters less than 1 mu m. A thin film of polystyrene (PS) prepared on a solid substrate was exposed to UFB water for 2 days at room temperature. The PS surface was characterized by X-ray photoelectron spectroscopy (XPS), static contact angle measurements in water, and atomic force microscopy (AFM). The surface chemical composition and wettability of PS films remained unchanged after treatment, so that aggregation states of PS at film surfaces remained unaltered by UFB water. On the other hand, after treatment, many UFBs were adsorbed on hydrophobic PS surfaces. To study the effect of UFBs on scaffold properties, the adsorption behavior of fibronectin, which is a typical extracellular matrix protein involved in cell adhesion and proliferation, was examined. While the effect on the adsorption was unclear, the structural denaturation of fibronectin was enhanced after UFB treatment, so that the proliferation of fibroblast cells on PS surfaces was promoted.. |
| 152. | T. Hirai, S. Osumi, H. Ogawa, T. Hayakawa, A. Takahara, K. Tanaka, Precise Synthesis and Surface Wettability of a Polymer with Liquid Crystalline Side Chains, Macromolecules, 10.1021/ma5010265, 47, 15, 4901-4907, 2014.08, Well-defined poly(methacrylate)s with liquid crystal side chains, designated as PPHM, were synthesized by a living anionic polymerization method. Introducing a short-length alkyl chain at the end of the side chain, the solubility of the polymer was improved, resulting in higher molecular weight polymers. While the highest weight-average molecular weight (M-w) of PPHM was 68k, it exceeded 100k for a slight-polydisperse PPHM. Wide-angle X-ray diffraction (WAXD) revealed that PPHM formed a smectic A phase with 2.7 nm layer spacing and that the layer structure is present even in the glassy state at room temperature. Molecular aggregation states of PPHM in surface regions of films were characterized by sum-frequency generation, grazing-incidence WAXD, and contact angle measurements. The results show that the PPHM with a larger M-w formed a layer structure parallel to the film plane. Although low M-w PPHM also maintained a layer structure, the structure became more random within internal regions. The surface reorganization of PPHM with larger M-w was suppressed in comparison with smaller ones.. |
| 153. | A. Shundo, Y. Hoshino, T. Higuchi, Y. Matsumoto, D. P. Penaloza Jr, K. Matsumoto, M. Ohno, K. Miyaji, M. Goto, K. Tanaka, Facile Microcapsule Fabrication by Spray Deposition of a Supramolecular Hydrogel, RSC Advances, 4, 68, 36097-36100, 2014.08. |
| 154. | M. Watanabe, H. Hagiwara, A. Iribe, Y. Ogata, K. Shiomi, A. Staykov, S. Ida, K. Tanaka, T. Ishihara, Spacer Effects in Metal-free Organic Dyes for Visible-light-driven Dye-sensitized Photocatalytic Hydrogen Production, Journal of Materials Chemistry A, 10.1039/c4ta02720e, 2, 32, 12952-12961, 2014.08. |
| 155. | A. Horinouchi, N. L. Yamada, K. Tanaka, Aggregation States of Polystyrene at Nonsolvent Interfaces, Langmuir, 10.1021/la500829p, 30, 22, 6565-6570, 2014.06. |
| 156. | T. Date, Y. Ueda, H. Atarashi, T. Sawada, H. Matsuzawa, K. Tanaka, T. Serizawa, Difference in Protein Adsorption Onto Polymer Films With or Without Thermal Annealing, Journal of Nanoscience and Nanotechnology, 10.1166/jnn.2014.8580, 14, 4, 3106-3111, 2014.04, Protein adsorptions onto non-annealed (NA) and thermally annealed (TA) polyetherimide films were examined by surface plasmon resonance measurements. Proteins adsorbed onto the NA films with smaller adsorption constants in comparison with the TA films. Neutron reflectivity measurements of the two films suggested that the outermost region of the NA films swelled with larger amounts of water molecules than the TA films. It is plausible that the aforementioned difference in the protein adsorption properties is derived from the difference in the interfacial aggregation structures of the two films.. |
| 157. | J. Zhan, H. Matsuno, H. Masunaga, O. Hiroki, K. Tanaka, Green Solid Films with Tunable Mechanical Properties Made from Deoxyribonucleic Acid, NPG Asia Materials, 10.1038/am.2014.4, 6, e92, 2014.03. |
| 158. | Y. Oda, A. Horinouchi, D. Kawaguchi, H. Matsuno, S. Kanaoka, S. Aoshima, K. Tanaka, Effect of Side-Chain Carbonyl Groups on the Interface of Vinyl Polymers with Water, Langmuir, 10.1021/la404802j, 30, 5, 1215-1219, 2014.02. |
| 159. | Y. Oda, K. Tanaka, Aggregation States and Molecular Motion of Well-Defined Vinyl Polymers at the Water Interface, 高分子論文集, 10.1295/koron.71.343, 71, 8, 343-351, 2014.01, [URL], We investigated the conformation of PMMA in thin films at the air-water interface by sum frequency generation (SFG) spectroscopy and discuss the effect of stereoregularity on the interfacial structure of PMMA. At the air interface, isotactic PMMA takes a helical conformation where the hydrophilic carbonyl groups are oriented towards the interfacial region of the film. Thus, even though the polymer chains come in contact with water, the chain conformation at the interface changes very little. The structure of syndiotactic PMMA at the air and water interfaces is significantly different. Poly(methyl 2-propenyl ether) (PMPE), synthesized via living cationic polymerization, is structurally similar to PMMA, but it lacks the carbonyl group. We discuss the effect of the carbonyl group on the water structure at the interface by comparing the results of our measurements to the previously reported PMMA-water system. This knowledge is crucial for the design and construction of highly-functionalized polymer interfaces for biological applications.. |
| 160. | A. Shundo, K. Tanaka, Mesoscopic Heterogeneity in Supramolecular Network Systems, 日本レオロジー学会誌, 10.1678/rheology.42.89, 42, 2, 89-95, 2014.01, [URL], Molecules are often assembled by themselves with a large aspect ratio, leading to the formation of network structure based on their entanglements. Such systems, so-called "supramolecular network systems" possess hierarchical structure with various length scales ranging from nanometer to micrometer. Thus, to give a better understanding of dynamics for the supramolecular network systems, it is necessary to examine the structure and physical properties at various length scales, and clarify the correlation. By using optical tweezers and particle tracking techniques, we here show the local rheological properties in a worm-like micelle solution and a supramolecular hydrogel, which are formed by the networks based on the self-assembly of the amphiphilic molecules in water. In these techniques, viscoelastic information can be accessed on the basis of the movement of probe particles dispersed in a sample to be measured. For the worm-like micelle solution, we found that the viscoelastic functions (G′ and G″ ) varied depending on the location measured and the location-dependent variation of G′ and G″ was observed only at the measurement timescale being shorter than the relaxation time. This can be understood by taking into account that there exists a concentration fluctuation in the solution. Such fluctuation can be regard as a spatial heterogeneity when one takes a snapshot of the solution at a time shorter than the relaxation time. Also, the heterogeneity in the rheological properties was observed in a sol obtained by physically disrupting the supramolecular hydrogel. The extent of the heterogeneity decreased as a solto-gel transition proceeded. Such homogenization was associated with the change in the network structure rather than that in the molecular assembled state, which remains comparable in the sol and gel.. |
| 161. | Y. Ogata, D. Kawaguchi, N. L. Yamada, K. Tanaka, Multistep Thickening of Nafion Thin Films in Water, ACS Macro Letters, 10.1021/mz400322q, 2, 10, 856-859, 2013.10. |
| 162. | A. Shundo, K. Hori, D.P. Penaloza Jr, K. Yoshihiro, A. Masahiko, K. Tanaka, Nonsolvents-induced Swelling of Poly(methyl methacrylate) Nanoparticles, Physical Chemistry Chemical Physics, 15, 39, 16574-16578, 2013.10. |
| 163. | D. Kawaguchi, K. Tanaka, Structures and Physical Properties at Surfaces and Interfaces of Polymers, Toraibarojisuto/Journal of Japanese Society of Tribologists, 58, 10, 742-749, 2013.10. |
| 164. | 川口大輔, 田中敬二, 高分子表面・界面の構造と物性の解明, トライボロジスト, 10.18914/tribologist.58.10_742, 58, 10, 742-749, 2013.10. |
| 165. | S. Shimomura, H. Matsuno, K. Tanaka, Effect of Mechanical Instability of Polymer Scaffolds on Cell Adhesion, Langmuir, 10.1021/la4027706, 29, 35, 11087-11092, 2013.09. |
| 166. | A. Shundo, K. Hori, T. Ikeda, N. Kimizuka, K. Tanaka, Design of a Dynamic Polymer Interface for Chiral Discrimination, Journal of the American Chemical Society, 10.1021/ja404701s, 135, 28, 10282-10285, 2013.07. |
| 167. | D. P. Penaloza Jr, A. Shundo, K. Matsumoto, M. Ohno, K. Miyaji, M. Goto, K. Tanaka, Spatial Heterogeneity in the Sol-gel Transition of a Supramolecular System, Soft Matter, 9, 21, 5166-5172, 2013.06. |
| 168. | A. Horinouchi, K. Tanaka, An Effect of Stereoregularity on the Structure of Poly(methyl methacrylate) at Air and Water Interfaces, RSC Advances, 3, 24, 9446-9452, 2013.06. |
| 169. | H. Atarashi, K. Tanaka, T. Hirai, K. Hori, M. Hino, H. Morita, T. Serizawa, Uptake of Water in As-spun Poly(methyl methacrylate) Thin Films, RSC Advances, 10.1039/c3ra23066j, 3, 11, 3516-3519, 2013.03. |
| 170. | A. Horinouchi, Y. Fujii, K. Tanaka, Interfacial Dynamics of Poly(methyl methacrylate) in Water, 4th International Symposium on Slow Dynamics in Complex Systems: Keep Going Tohoku 4th International Symposium on Slow Dynamics in Complex Systems Keep Going Tohoku, 10.1063/1.4794616, 1518, 459-461, 2013.03, [URL], Aggregation states of polymers at the surface generally tend to alter to their most stable ones in response to their surrounding environment. We here apply a time-resolved contact angle measurement to examine the rate of the surface reorganization of poly(methyl methacrylate) (PMMA) in water. By doing these measurements at various temperatures, it is possible to extract the apparent activation energy of the surface dynamics based on the relation of the surface relaxation time and temperature. Also, sum-frequency generation spectroscopy revealed that the surface reorganization involves the conformational changes in the main chain portion as well as the side chains. Hence, the dynamics observed here might reflect the segmental motion at the outermost region of the PMMA film, in which water plays as a plasticizer.. |
| 171. | M. Haraguchi, T. Hirai, M. Ozawa, K. Miyaji, K. Tanaka, Hydrophobic Acrylic Hard Coating by Surface Segregation of Hyper-Branched Polymers, Applied Surface Science, 10.1016/j.apsusc.2012.11.160, 266, 235-238, 2013.02, The ability of hyperbranched polymers (HBPs) to preferentially segregate to the surface of its matrix owing to its unique structure makes it a good candidate as a surface modifier. One particular challenge in its application as an efficient surface modifier, however, is its possible elimination from the surface due to the lack of attachments between a HBP (modifier) and its host material (polymer matrix). Here, we present a novel approach to efficiently prevent the removal of HBPs from the surface of its host material by directly reacting a HBP containing fluoroalkyl segments (F-HBP) to a multi-functional acrylate monomer prior to curing. We also have characterized surface structure and wettability of the acrylic hard coating material by X-ray photoelectron spectroscopic and contact angle measurements, respectively. The results show that since F-HBP was segregated at the surface, the surface became hydrophobic and more stable. Thus, we claim that our approach results in the formation of a water-repellent acrylic hard coating material. (C) 2012 Elsevier B.V. All rights reserved.. |
| 172. | H. Tsuruta, Y. Ikinaga, Y. Fujii, K. Tanaka, A Simple Approach for Surface Hardening of Polystyrene, Applied Surface Science, 10.1016/j.apsusc.2012.10.070, 264, 1, 589-592, 2013.01. |
| 173. | Y. Fujii, H. Morita, A. Takahara, K. Tanaka, Mobility Gradient of Polystyrene in Films Supported on Solid Substrates, Glass Transition, Dynamics and Heterogeneity of Polymer Thin Films, 10.1007/12_2012_175, 1-28, 2013.01, [URL], In this review, we show the distribution of glass transition temperature (T g) in monodisperse polystyrene (PS) films coated on silicon oxide layers along the direction normal to the surface. Scanning force microscopy with a lateral force mode revealed that surface T g () was lower than the corresponding bulk T g (). Interestingly, the glass transition dynamics at the surface was better expressed by an Arrhenius equation than by a Vogel-Fulcher-Tamman equation. Interdiffusion experiments for PS bilayers at various temperatures, above and below, enabled us to gain direct access to the mobility gradient in the surface region. T g at the solid substrate was examined by fluorescence lifetime measurements using evanescent wave excitation. The interfacial T g was higher than the corresponding. The extent of the elevation was a function of the distance from the substrate and the interfacial energy. The T g both at the surface and interface was also studied by the coarse-grained molecular dynamics simulation. The results were in good accordance with the experimental results. Finally, dynamic mechanical analysis for PS in thin and ultrathin films was made. The relaxation time for the segmental motion became broader towards the faster and slower sides, due probably to the surface and interfacial mobility. Graphical Abstract:. |
| 174. | A. Shundo, D. P. Penaloza, K. Tanaka, Microscopic Heterogeneity in Viscoelastic Properties of Molecular Assembled Systems, Chinese Journal of Polymer Science, 10.1007/s10118-013-1193-z, 31, 1, 1-11, 2013.01, An important step in understanding molecular assembled systems is to examine the structure and physical properties at various length scales and clarify the correlation between them. However, while the structures of these systems have been extensively studied from nanoscopic to macroscopic scales, their viscoelastic properties have been often limited to bulk rheological measurements. By using optical tweezers and particle tracking, we here show the local viscoelastic properties and their spatial distributions for the following systems: worm-like micelle solution, supramolecular hydrogel and lyotropic liquid crystal, which are formed by self-assembly of amphiphilic molecules in water. We found that all systems studied possessed a spatial heterogeneity in their viscoelastic properties and this was originated from the heterogeneous structures. It is interesting to note that there is the heterogeneity with the characteristic length scale of sub-micrometer or micrometer scale, thereby structures, although the systems are formed by molecules with nanometer size. The findings of these studies should lead to a better understanding of the dynamics of such systems.. |
| 175. | A. Shundo, K. Hori, D. P. Penaloza Jr, K. Tanaka, Optical Tweezers with Fluorescence Detection for Temperature-Dependent Microrheological Measurements, Review of Scientific Instruments, 10.1063/1.4789429, 84, 1, 2013.01, We introduce a setup of optical tweezers, capable of carrying out temperature-dependent rheological measurements of soft materials. In our setup, the particle displacement is detected by imaging a bright spot due to fluorescence emitted from a dye-labeled particle against a dark background onto a quadrant photodiode. This setup has a relatively wide space around the sample that allows us to further accessorize the optical tweezers by a temperature control unit. The applicability of the setup was examined on the basis of the rheological measurements using a typical viscoelastic system, namely a worm-like micelle solution. The temperature and frequency dependences of the local viscoelastic functions of the worm-like micelle solution obtained by this setup were in good accordance with those obtained by a conventional oscillatory rheometer, confirming the capability of the optical tweezers as a tool for the local rheological measurements of soft materials. Since the optical tweezers measurements only require a tiny amount of sample (∼40 μL), the rheological measurements using our setup should be useful for soft materials of which the available amount is limited. © 2013 American Institute of Physics.. |
| 176. | 菊地貴子, 大武義人, 仲山和海, 堀雅文, 田中敬二, 再生ポリカーボネートの判別手法の開発, 高分子論文集, 68, 11, 731-736, 2012.11. |
| 177. | C. Zhang, Y. Fujii, K. Tanaka, Effect of Long Range Interactions on the Glass Transition Temperature of Thin Polystyrene Films, ACS Macro Letters, 10.1021/mz300391g, 1, 11, 1317-1320, 2012.11, The glass transition temperature (T-g) of thin polystyrene (PS) films supported on silicon wafers with oxide layers of varying thickness was characterized by the temperature dependence of the film thickness using ellipsometry. This allowed us to uncover how a long-range interaction affects the T-g of polymer films. As previously reported using a variety of methods, the T-g decreased with decreasing film thickness. However, the extent was not the same among the reports. In this study, we found that the T-g attenuation of a PS film of a given thickness was dependent on the oxide layer thickness of the silicon wafer via the long-range interaction.. |
| 178. | Y. Fujii, K. Tanaka, Thermal Molecular Motion of Poly(methyl methacrylate) at Various Interfaces, 日本レオロジー学会誌, 10.1678/rheology.40.143, 40, 3, 143-149, 2012.10, [URL], Thermal molecular motion of poly(methyl methacrylate) (PMMA) at various interfaces, gases and liquids, was discussed. The α a- and β-relaxation processes were clearly observed even at the air interface. Both relaxation temperatures at the air interface were lower than the corresponding ones in the bulk. In addition, the extent to which the peak temperature for the surface relaxation processes fell below that of the bulk strongly depended on the stereoregularity of the films. Then, thermal molecular motion of PMMA was analyzed at gaseous carbon dioxide (CO 2) interface. It was more enhanced than that at gaseous nitrogen interface because CO 2 molecules were sorbed in the interfacial region, which played as plasticizing agents. Finally, mechanical properties of PMMA were also studied at interfaces with liquids such as water, hexane and methanol. The modulus decreased closer to the outermost region of the film. The extent to which the modulus decreased in the interfacial region was consistent with the amount of liquid sorbed into the film. Therefore, it can be claimed that interfacial molecular motion of polymers can be regulated on the basis of the aggregation states.. |
| 179. | A. Matsubayashi, K. Fukunaga, K. Tanaka, Metal Ions/ion Clusters Transport in Glassy Polymer Films: Construction of Multi-layered Polymer and Metal Composite Films, Journal of Materials Chemistry, 10.1039/c2jm31923c, 22, 31, 15578-15585, 2012.08. |
| 180. | M. Haraguchi, T. Hirai, M. Ozawa, M. Miyamoto, K. Tanaka, One-step Synthesis of Hyper-branched Polymer with Perfluoroalkyl Segments, KGK-KAUTSCHUK GUMMI KUNSTSTOFFE, 65, 7-8, 34-38, 2012.07, Initiator-fragment incorporation radical polymerization (IFIRP) of commercially available fluorinated monomers was performed in the presence of cross-linking agents, resulting in a hyperbranched polymer with perfluoroalkyl groups (F-HBP). In our one-step method, a F-HBP was successfully prepared without gelation within 1 h. The F-HBP exhibited interesting properties based on both the hyperbranched architecture and the perfluoroalkyl groups, such as good solubility in common organic solvents, high thermal stability, and low surface free energy.. |
| 181. | A. Horinouchi, H. Atarashi, Y. Fujii, K. Tanaka, Dynamics of Water-Induced Surface Reorganization in Poly(methyl methacrylate) Films, Macromolecules, 10.1021/ma3002559, 45, 11, 4638-4642, 2012.06, At the outermost surface, aggregation states of polymers generally tend to alter to their most stable ones in response to their surrounding environment. We here apply a time-resolved contact angle measurement to study the rate of the surface reorganization of poly(methyl methacrylate) (PMMA) in water. By doing these measurements at various temperatures, it is possible to determine the apparent activation energy of the surface dynamics based on the relation of the surface relaxation time and temperature. Also, the sum-frequency generation spectroscopy revealed that the surface reorganization involves the conformational changes in the main chain part as well as the side chains. Hence, the dynamics observed here may reflect the segmental motion at the outermost region of the PMMA film, in which water plays as a plasticizer.. |
| 182. | H. Tsuruta, Y. Fujii, N. Kai, H. Kataoka, T. Ishizone, M. Doi, H. Morita, K. Tanaka, Local Conformation and Relaxation of Polystyrene at Substrate Interface, Macromolecules, 10.1021/ma3007202, 45, 11, 4643-4649, 2012.06, The local conformation of polymer chains in a film at a substrate interface was examined by sum-frequency generation spectroscopy. When a polystyrene (PS) film was prepared on a quartz substrate by a spin-coating method, the chains were aligned in the interfacial plane of the substrate. A dissipative particle dynamics simulation revealed that a spinning torque induced the chain orientation during the film preparation process and the extent of the orientation was a function of the distance from the interface. This interfacial orientation of chains was not observed for a PS film prepared by a solvent-casting method. Interestingly, the local conformation of chains at the substrate interface was unchanged even at a temperature that was 80 K higher than the bulk glass transition temperature (T-g). This observation means that polymer chains at the substrate interface can be only partially relaxed under conditions where the bulk chains are fully relaxed. On the other hand, interfacial chains could be easily relaxed by solvent annealing.. |
| 183. | K. Hori, D. P. Penaloza, A. Shundo, K. Tanaka, Time-Dependent Heterogeneity in Viscoelastic Properties of Worm-Like Micelle Solutions, Soft Matter, 10.1039/c2sm25549a, 8, 28, 7361-7364, 2012.05. |
| 184. | D. P. Penaloza, K. Hori, A. Shundo, K. Tanaka, Spatial Heterogeneity in a Lyotropic Liquid Crystal with Hexagonal Phase, Physical Chemistry Chemical Physics, 10.1039/c2cp40284j, 14, 15, 5247-5250, 2012.04, [URL], Non-ionic surfactant hexaethylene glycol, C 12E 6, in water self-assembles into various kinds of mesophases by varying the surfactant concentration. A spatial heterogeneity was discussed on the basis of the diffusion of probe particles dispersed in the C 12E 6-water solution. Interestingly, at 50 wt% C 12E 6 where the hexagonal structure was formed, two kinds of motion of probe particles were observed: some particles normally diffused while others were restricted, indicating the existence of a heterogeneity in the physical properties. Such heterogeneity can be explained in terms of heterogeneous structures composed of hexagonal domains with isotropic-like regions.. |
| 185. | H. Tsuruta, Y. Fujii, K. Tanaka, One-Pot Surface Modification of Rubbery Polymer Films, Polymer Chemistry, 10.1039/c1py00488c, 3, 2, 319-321, 2012.02, [URL], A novel method to modify the surface of rubbery polymer films on the basis of the preferential segregation of inorganic materials fed into the system in tiny amounts is proposed. The surface so prepared had several prominent properties such as surface hardness, anti-oxidant properties, transparency, and so forth.. |
| 186. | 松野寿生, 平田豊章, 田中賢, 田中敬二, 高分子/水界面における凝集構造と生体適合性, 電子情報通信学会技術研究報告. OME, 有機エレクトロニクス, 111, 440, 37-38, 2012.02, 安定かつ平坦なポリ(アクリル酸2-メトキシエチル)(PMEA)表面を,ポリメタクリル酸メチル(PMMA)とブレンドすることで作製した.水中におけるPMEA/PMMAブレンド膜に対する気泡接触角は時間依存的に変化し,水界面近傍における分子鎖凝集構造が再編成されることが分かった.PMEA/PMMAブレンド表面は,従来のPMEA膜と同等以上の血小板粘着抑制能を示し,優れた血液適合性を有することが分かった.. |
| 187. | T. Hirai, K. Kawasaki, K. Tanaka, Interfacial Kinetics of a Model Epoxy-Amine Addition Reaction, Phys. Chem. Chem. Phys., 14, 39, 13532-13534, 2012.01, 本論文はエポキシ/アミンのモデル反応に基づき、固体界面近傍における反応動力学評価を行ったものである。活性化エネルギー、衝突頻度因子の算出から、反応の活性化エネルギーはバルク、界面で不変である一方、バルクの衝突頻度因子は界面近傍におけるそれと比較して6倍程度であった。このことから、固体界面の存在はエポキシ硬化反応の化学的な因子には影響を与えず、物理的因子に大きな影響を与えることを明らかにした。. |
| 188. | A. Shundo, Y. Okada, F. Ito, K. Tanaka, Fluorescence Behavior of Dyes in Thin Films of Various Polymers, Macromolecules, 10.1021/ma201901x, 45, 1, 329-335, 2012.01, We have studied the fluorescence behavior of a dye, 6-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)hexanoic acid (NBD), in thin films of polymers with various polarities, such as poly(methyl rnethacrylyate) (PMMA), Arton, poly(styrene) (PS), hydrogenated polystyrene (H-PS), and Zeonex. In the case of well-dispersed systems,.the fluorescence behavior of NBD could - be explained in terms of the mobility of the polymer matrix. This was the case for PMMA, Arton, and PS. On the other hand, when H-PS or Zeonex was.used, NBD aggregated in the films, leading to unusual fluorescence behavior: the fluorescence lifetime and maximum wavelength increased with a decrease in the film thickness. Time- and space-resolved fluorescence spectroscopy using an evanescent wave excitation revealed that the aggregation states of NBD near the interface varied with the film thickness, While NBD molecules near the interface aggregated in a thick film, such was not the case in a thin film. Angular dependent X-ray photoelectron spectroscopy (ADXPS) structurally confirmed the above observations; that is, the film thickness greatly influenced the depth profile of the NBD composition in the polymer films.. |
| 189. | K. Hori, H. Matsuno, K. Tanaka, Sorption Kinetics of Methanol in Thin Poly(methyl methacrylate) Films Studied by Optical Reflectivity, Soft Matter, 10.1039/c1sm06098h, 7, 21, 10319-10326, 2011.11, [URL], To study the thickness dependence of methanol diffusion into poly(methyl methacrylate) (PMMA) films, an experimental method based on optical reflectivity was proposed. The method can cover a thickness range from the micrometre down to the nanometre scale using a single set-up. Methanol molecules diffuse into PMMA following a Case II mechanism in which they induce segmental motion of the matrix polymer. We observed two diffusion modes, fast and slow, assignable respectively to the outermost layer and the remaining internal region including the substrate interface. When the film becomes thinner, the ratio of the interfacial area to the total volume increases. This results in slowing down of the methanol diffusion due to the contribution of the depressed segmental mobility at the substrate interface. Interestingly, the thickness of the mobility-enhanced layer at the outermost region of the film similarly decreased with decreasing total thickness owing to the effect of the substrate interface.. |
| 190. | 菊地貴子, 大武義人, 仲山和海, 堀雅文, 田中敬二, 再生ポリカーボネートの判別手法の開発, 高分子論文集, 10.1295/koron.68.731, 68, 11, 731-736, 2011.11, [URL], 資源循環型社会の構築を目指して，材料のリサイクルが推奨されている．リサイクル表示の偽造を抑制し信頼性を確保するため，再生プラスチック製品の判別手法の確立が急務となっている．プラスチックはその成形加工時や使用時に熱的・機械的なダメージを受けている．このため，再生プラスチックの外的要因による劣化速度は，未使用品と比較して，速くなることが予想される．本研究では，光照射による劣化促進度を評価することで再生ポリカーボネートを判別することに成功した． . |
| 191. | A. Matsubayashi, K. Fukunaga, T. Tsuji, K. Ataka, H. Ohsaki, K. Tanaka,, Band-selective Mirror Characteristics of Polymer/Metal Multilayer Films, Chem. Lett., 10.1246/cl.2011.1138, 40, 10, 1138-1139, 2011.10. |
| 192. | H. Atarashi, Y. Fujii, D. Yamazaki, M. Hino, H. Morita, K. Tanaka, Density Distributions of Poly (methyl methacrylate) Thin Films in Non-Solvents, 高分子論文集, 10.1295/koron.68.608, 68, 9, 608-615, 2011.09, [URL], Recently, polymeric materials nave oeen widely used in applications sucn as medical materiais, in tnese applications, the surrace comes into contact with a different phase. Thus, their interfaces should be studied, both their structures as well as their dynamics. The density profiles of a perdeuterated poly(methyl methacrylate) (dPMMA) film in water, hexane, methanol, ethanol, 1-propanol, and 1-butanol were examined along the direction normal to the interface by neutron reflectivity (NR). Although these liquids are typical non-solvents for dPMMA, the liquid/polymer interfaces were diffuse in comparison with the air/polymer interface probably due to the partial dissolution of polymer segments at the outermost region of the film. Interestingly, in water, an anomalous swollen layer was formed beneath the diffused interface. On the other hand, such a swollen layer was not observed for the dPMMA films in alcohols. This is simply because alcohol molecules deeply penetrated into the films. The amounts of the alcohols penetrated are related to the interaction parameter. The fractional amount of nonsolvents at the substrate interface was higher than that in the internal region of the film.. |
| 193. | A. Shundo, K. Mizuguchi, M. Miyamoto, M. Goto, K. Tanaka, Controllable Heterogeneity in a Supramolecular Hydrogel, Chemical Communications, 10.1039/c1cc12733k, 47, 31, 8844-8846, 2011.08, A dispersion of a peptide amphiphile into water forms hierarchical fibril structures, leading to a supramolecular hydrogel. We here report that there exists dynamic heterogeneity in the gel, which might be induced by the heterogeneous fibril network. The network, and therefore, the heterogeneity, can be easily regulated by changing the temperatures used to dissolve the gelator in water. © 2011 The Royal Society of Chemistry.. |
| 194. | 田中敬二, 高分子ナノ薄膜における物性解析法の確立, 日本ゴム協会誌, 84, 7, 212-212, 2011.07. |
| 195. | S. Miwa, T. Kikuchi, Y. Ohtake, K. Tanaka, Surface Degradation of Poly(ethylene-co-propylene-co-5-ethylidene-2-norbornene) Terpolymer by Ozone in Water, Polym. Degrad. Stab., 10.1016/j.polymdegradstab.2011.05.001, 96, 8, 1503-1507, 2011.05. |
| 196. | T. Hirai, L. Huan, Y. Ohta, T. Yokozawa, K. Tanaka, Surface Segregation of Well-defied N-Substituted Hyperbranched Polyamides in Linear Polymer Matrix, Chemistry Letters, 10.1246/cl.2011.366, 40, 4, 366-367, 2011.04, Surface segregation of well-defined N-substituted hyperbranched polyamides (HBPA) with various side chain lengths in linear polystyrene matrix was studied. To what extent HBPA was segregated at the surface was dependent on the side chain length, which regulated intermolecular interactions among HBPA molecules via steric hindrance.. |
| 197. | K. Tanaka, Y. Fujii, Polymer Structure and Physical Properties at Non-solvent Interfaces, 高分子, 60, 3, 148-152, 2011.03, Interfaces of polymers with "non-solvents" play an important role in their functional properties such as wettability, friction with lubricants, cell adhesion, and biocompatibility. To design and construct highly functionalized polymers for applications that exploit these characteristics, aggregation states of the polymers at the liquid interfaces must be understood as the first benchmark. However, this is experimentally difficult because such interfaces are buried. In this review, we introduce recent development of the issue with the advent of modem experimental techniques.. |
| 198. | T. Hirata, H. Matsuno, M. Tanaka, K. Tanaka, Surface Segregation of Poly(2-methoxyethyl acrylate) in a Mixture with Poly(methyl methacrylate), Physical Chemistry Chemical Physics, 10.1039/c0cp02101f, 13, 11, 4928-4934, 2011.03, [URL], Poly(2-methoxyethyl acrylate) (PMEA) exhibits excellent blood compatibility. To understand why such a surface functionality exists, the surface of PMEA should be characterized in detail, structurally and dynamically, under not only ambient conditions, but also in water. However, a thin film of PMEA supported on a solid substrate can be easily broken, namely it is dewetted. Our strategy to overcome this difficulty is to mix PMEA with poly(methyl methacrylate) (PMMA). Differential scanning calorimetry and cloud point measurements revealed that the PMEA/PMMA blend has a phase diagram with a lower critical solution temperature. The blend surface was also characterized by X-ray photoelectron spectroscopy in conjunction with microscopic observations. Although PMEA is preferentially segregated over PMMA at the blend surface due to its lower surface free energy, the extent of segregation in the as-prepared films was not sufficient to cover the surface. Annealing the blend film at an appropriate temperature, higher than the glass transition temperature and lower than the phase-separation temperature of the blend, enabled us to prepare a stable and flat surface that was perfectly covered with PMEA.. |
| 199. | 田中敬二, 藤井義久, 非溶媒界面における高分子の凝集状態と熱運動特性, 高分子, 60, 3, 148-152, 2011.03, Interfaces of polymers with "non-solvents" play an important role in their functional properties such as wettability, friction with lubricants, cell adhesion, and biocompatibility. To design and construct highly functionalized polymers for applications that exploit these characteristics, aggregation states of the polymers at the liquid interfaces must be understood as the first benchmark. However, this is experimentally difficult because such interfaces are buried. In this review, we introduce recent development of the issue with the advent of modem experimental techniques. © 2011 The Society of Polymer Science, Japan.. |
| 200. | H. Matsuno, J. Nakahara, K. Tanaka, Dynamic Mechanical Properties of Solid Films of Deoxyribonucleic Acid, Biomacromolecules, 10.1021/bm1010933, 12, 1, 173-178, 2011.01, Solid films of deoxyribonucleic acid (DNA) from salmon testes were prepared by a solvent-casting method. The thermal molecular motion of the DNA film was examined by dynamic mechanical analysis (DMA). Four absorption peaks and one shoulder of the loss modulus were observed in the temperature domain from approximately 150 to 490 K. To assign these, thermal analysis employing thermogravimetry (TG) and differential thermal analysis (DTA) was used in cc junction with ultraviolet (UV)-visible and Fourier-transform infrared (FT-IR) spectroscopy. It seems most likely that, in order of increasing temperature, they are a B-I -> B-II, conformational transition, a relatively large-scale movement associated with water molecules, water evaporation, thermal denaturation of DNA, and a glass transition.. |
| 201. | N. Idota, K. Nagase, K. Tanaka, T. Okano, M. Annaka, Stereoregulation of Thermoresponsive Polymer Brushes by Surface-Initiated Living Radical Polymerization and the Effect of Tacticity on Surface Wettability, Langmuir, 10.1021/la1024229, 26, 23, 17781-17784, 2010.12, In this study, stereocontrolled poly(N-isopropylacrylamide) (PIPAAm) brushes were grafted from surfaces by atom transfer radical polymerization (ATRP) in the presence of a Lewis acid, and the effect of PIPAAm brash tacticity on the thermoresponsive wettabiliy was investigated. PIPAAm grafted by ATRP in the presence of Y(OTf)(3) showed high isotacticity, while the control brush polymerized in the absence of Y(OTf)(3) was clearly atactic. The isotacticity and molecular weight of PIPAAm brushes were controlled by polymerization conditions. The wettability of isotactic PIPAAm-grafted surfaces decreased slightly below 10 degrees C, although the phase transition temperature of atactic surface was 30 degrees C, and the bulk isotactic polymer was water-insoluble between 5 and 45 degrees C.. |
| 202. | 三輪怜史, 菊地貴子, 大武義人, 田中敬二, オゾン水中におけるエチレン‐プロピレン‐ジエン三元共重合体の劣化機構, 日本ゴム協会誌, 83, 10, 324-330, 2010.10. |
| 203. | I. Narayama, D. Baba, A. Takahara, K. Tanaka, Direct Observation of Surface and Internal Phase-separated Structure of the Active Layer Buried in Organic Photovoltaic Cells, Appl. Surface Sci, 257, 1145-1148, 2010.09. |
| 204. | A. Horinouchi, Y. Fujii, N. L. Yamada, K. Tanaka, Surface Reorganization of Thin Poly(methyl methacrylate) Films Induced by Water, Chemistry Letters, 10.1246/cl.2010.810, 39, 8, 810-811, 2010.08, Neutron reflectivity revealed that the surface aggregation states of poly(methyl methacrylate) film can be altered by water, which is a typical nonsolvent, in a relatively large scale.. |
| 205. | Y. Tateishi, N. Kai, H. Noguchi, K. Uosaki, T. Nagamura, K. Tanaka, Local Conformation of Poly(methyl methacrylate) at Nitrogen and Water Interfaces, Polymer Chemistry, 10.1039/b9py00227h, 1, 3, 303-311, 2010.05, [URL], The local conformation of poly(methyl methacrylate) (PM MA) chains at the nitrogen (N-2) and water interfaces was studied by infrared-visible sum-frequency generation (SFG) spectroscopy. Although SFG spectra in the C-H region for PMMA at the N-2 interface have been hitherto reported, the peak assignments are not in accord with one another. Thus, we first made accurate assignments of SFG peaks using films, which had been well annealed at a temperature above the glass transition temperature for a long time, of three different deuterated PMMAs as well as normal protonated PMMA. At the N-2 interface, hydrophobic functional groups such as a methyl, ester methyl and methylene groups were present. While the a methyl group was oriented along the direction parallel to the interface, ester methyl and methylene groups were oriented normal to the interface. Quantitative discussion concerning the orientation of the functional groups of PMMA at the N-2 interface was aided by a model calculation. Once the PMMA film contacted water, the carbonyl groups of the PMMA side chains were oriented to the water phase to form hydrogen bonds with water molecules, resulting in the migration of ester methyl into the internal region of the film. Concurrently, the methylene groups became randomly oriented at the water interface and/or in part migrated into the internal region. Interestingly, the a methyl groups still existed at the water interface oriented along the parallel direction. The outermost region of PMMA in water can consist of hydrophilic and hydrophobic domains with sub-nanometre scale. Water molecules H-bond to themselves near the hydrophobic domains, leading to the formation of an ice-like structure of water molecules. However, water molecules adjacent to the hydrophilic domains H-bond with carbonyl groups.. |
| 206. | Y. Fujii, T. Nagamura, K. Tanaka, Relaxation Behavior of Poly(methyl methacrylate) at a Water Interface, Journal of Physical Chemistry B, 10.1021/jp909373g, 114, 10, 3457-3460, 2010.03, The relaxation behavior of poly(methyl methacrylate) (PMMA), spin-coated oil a silicon wafer, at the water interface was examined by lateral force microscopy as a function of temperature and scanning rate. Even in water, the lateral force peak which was assigned to the segmental motion of PMMA plasticized by water Molecules was clearly observed in the temperature domain. The apparent activation energy For the plasticized alpha(a)-relaxation process was Much smaller than those for the original alpha(a)-relaxation processes at the intact surface and in the bulk. The depth profile of the glass transition temperature (T-g) of the PMMA film in water was obtained, showing that T-g decreases with proximity to the water phase, The T-g. depression observed here was best explained in terms of the water Content of the film, rather than a confinement effect.. |
| 207. | H. Atarashi, H. Morita, D. Yamazaki, M. Hino, T. Nagamura, K. Tanaka, Swelling Structure of Thin Poly(methyl methacrylate) Films in Various Alkyl Length Alcohols, J. Phys. Chem. Lett. , 1, 5, 881-885 , 2010.02. |
| 208. | 道下浩征, 赤堀敬一, 田中敬二, 松本広重, 春田大蔵, 永田吉憲, 山本壽昭, 石原達己, ナフィオン膜の電解条件下での安定性に及ぼす圧力の影響, Electrochemistry, 78, 1, 42-49 , 2010.01. |
| 209. | H. Michishita, K. Akabori, K. Tanaka, H. Matsumoto, D. Haruta, Y. Nagata, N. Yamamoto, T. Ishihara, Effects of Pressure on Stability of Nafion Membrane under Water Electrolysis, Electrochemistry, 10.5796/electrochemistry.78.42, 78, 1, 42-49, 2010.01, In previous study, proton conductivity increased with increasing pressure under water electrolysis, so the effects of pressure on the stability of Nafion 117 have been studied. It was found that conductivity of Nafion 117 drastically decreased at initial few h and then gradually decreased in the following period under electrolysis condition. Decrease in conductivity can be explained by decomposition of Nafion 117. Decomposition of Nafion 117 is accelerated by increasing pressure. Solid state NMR, IR, and Raman spectroscopy suggested that the electrochemical oxidation of sulfo group was occurred at initial period followed by decomposition of CFn main or side chain. Therefore, initial increase in resistance can be explained by desorption of sulfo group in Nafion 117. Desorption of sulfo, group also forms pin hole in Nafion membrane which may cause gas leakage under water electrolysis. Mechanical strength of Nafion membrane is also drastically decreased at initial electrolysis period. Consequently, chemical stability of Nafion 117 may cause serious problem for water electrolysis application and this study reveals that increasing pressure strongly accelerates the decomposition of Nafion 117.. |
| 210. | Y. Fujii, Z. Yang, J. Leach, H. Atarashi, K. Tanaka, O. K. C. Tsui, Affinity of Polystyrene Films to Hydrogen-Passivated Silicon and Its Relevance to the T-g of the Films, Macromolecules, 10.1021/ma901851w, 42, 19, 7418-7422, 2009.10, Qualitatively different thickness dependences have been observed in the glass transition temperature, T-g of polystyrene (PS) films supported by hydrogen-passivated silicon (H-Si). It has been suggested that upon annealing at high temperatures in air, the polymer/substrate interface of these films (i.e., PS/Si), though buried underneath the PS layer, might be oxidized, rendering the films a different polymer/ substrate interface (i.e., PS/SiOx-Si), which may account for the different thickness dependences of the T-g observed. In this experiment, we examine if the buried Substrate interface of PS/H-Si films can indeed be oxidized by annealing the films at 150 degrees C in air. Our result shows that a residual film does form on top of the H-Si surface, but it is a bound layer of PS. X-ray photoelectron spectroscopic (XPS) analyses and independence of the residual film oil the initial PS thickness evidence that the H-Si substrate buried underneath a PS film is not oxidized by annealing. We discuss a possible explanation to how the different thickness dependences may be observed in the T-g of these films.. |
| 211. | K. Akabori, H. Atarashi, M. Ozawa, T. Kondo, T. Nagamura, K. Tanaka, Glass Transition Behaviour of Hyper-branched Polymers, Polymer, 50, 20, 4868-4875, 2009.09. |
| 212. | I. Narayama, K. Akabori, H. Morita, T. Nagamura, K. Tanaka, Nanoscopic Adhesion Test for Polymers by A Light-lever System, J. Phys. Conf. Ser. , 184, 012032 , 2009.09. |
| 213. | Y. Fujii, H. Atarashi, M. Hino, T. Nagamura, K. Tanaka, Interfacial Width in Polymer Bilayer Films Prepared by Double-Spin-Coating and Flotation Methods, ACS Applied Materials & Interfaces, 10.1021/am9004336, 1, 9, 1856-1859, 2009.09, A spin-coating method with the aid of selective solvents has been used to construct m,u. Itilayer struct ures for organic devices under the assumption that the solvents do not invade, a preformed structure. To confirm the assumption, we examined the interfacial width (lambda(i)) of model polymer bilayers, composed of polystyrene and perdeuterated poly(methyl methacrylate), prepared by spin-coating and notation methods. Neutron reflectivity measurements revealed that the lambda(i) value was,larger for the spin-coating method than for the flotation method. These results cast doubt on the validity of the assumption. This knowledge should be kept in mind when this method is applied to construct multilayer structures.. |
| 214. | T. Date, M. Ishikawa, K. Hori, K. Tanaka, T. Nagamura, M. Iwahashi and T. Serizawa, Water Droplets for the Symmetric Adhesion of Two Poly(methyl methacrylate) Films, Chem. Lett., 38, 7, 660-661, 2009.05. |
| 215. | 長村利彦, 田中敬二, 高分子超薄膜の界面物性評価とデバイス応用, 電子情報通信学会技術研究報告. OME, 有機エレクトロニクス, 109, 48, 1-2, 2009.05, 近年のナノテクノロジーの発展に伴い、複雑かつ微細な構造を有する高分子ナノ組織体の構築が実現しつつある。しかしながら、これらを指向した研究の多くはナノサイズ材料の創製やその機能特性に関するものであり、ナノ材料同士を任意に接合する技術はほとんど検討されていない。演者らは、これまで、高分子表面のダイナミクスを詳細に検討してきた。その結果、表面近傍では、バルクのガラス転移温度(T_g^b)以下の温度においても、比較的大きなスケールの分子運動が開放されることを明らかにしている。また、二枚の高分子膜を貼り合わせて調製した二層膜を表面のガラス転移温度(T_g^s)以上、T_g^b以下の温度で熱処理すると、界面層でのみセグメント拡散が起こり、接着力が発現することも明らかにした。ここでは、接着界面層だけでなく、被着面積もナノレベルにスケールダウンした際の接着力とその発現機構について考察する。. |
| 216. | K. Tanaka, Y. Tateishi, Y. Okada, T. Nagamura, M. Doi, H. Morita, Interfacial Mobility of Polymers on Inorganic Solids, Journal of Physical Chemistry B, 10.1021/jp810370f, 113, 14, 4571-4577, 2009.04, [URL], The segmental mobility of a typical amorphous polymer, polystyrene, at the interfaces with solid substrates was noninvasively examined by fluorescence lifetime measurements using evanescent wave excitation in conjunction with coarse-grained molecular dynamics simulation. The glass transition temperature (T(g)) was discernibly higher at the interface than in the internal bulk region. Measurements at different incident angles of excitation pulses revealed that T(g) became higher closer to the interface. The gradient became more marked with an increasing difference in the free energy at the interface between the polymer and solid substrate. The T(g) value at the interface decreased with decreasing molecular weight. However, the decrement for the interfacial T(g) was not as much as that for the bulk T(g), due to the restriction of chain end portions by the substrate. Finally, it was observed that when a film became thinner than 50 nm, the depressed mobility at the interface coupled with the enhanced mobility induced by the presence of the surface. The experimental and simulation results were in good accord with each other.. |
| 217. | A. Takahara, K. Tanaka, IUMRS-ICA 2008 symposium, sessions X. applications of synchrotron radiation and neutron beam to soft matter science and Y. frontier of polymeric nano-soft-materials - Precision polymer synthesis, self-assembling and their functionalization, Journal of Physics: Conference Series, 10.1088/1742-6596/184/1/011001, 184, 2009.01, [URL], Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science (Symposium X of IUMRS-ICA2008) Toshiji Kanaya, Kohji Tashiro, Kazuo Sakura Keiji Tanaka, Sono Sasaki, Naoya Torikai, Moonhor Ree, Kookheon Char, Charles C Han, Atsushi Takahara This volume contains peer-reviewed invited and contributed papers that were presented in Symposium X Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science at the IUMRS International Conference in Asia 2008 (IUMRS-ICA 2008), which was held on 9-13 December 2008, at Nagoya Congress Center, Nagoya, Japan. Structure analyses of soft materials based on synchrotron radiation (SR) and neutron beam have been developed steadily. Small-angle scattering and wide-angle diffraction techniques clarified the higher-order structure as well as time dependence of structure development such as crystallization and microphase-separation. On the other hand, reflectivity, grazing-incidence scattering and diffraction techniques revealed the surface and interface structural features of soft materials. From the viewpoint of strong interests on the development of SR and neutron beam techniques for soft materials, the objective of this symposium is to provide an interdisciplinary forum for the discussion of recent advances in research, development, and applications of SR and neutron beams to soft matter science. In this symposium, 21 oral papers containing 16 invited papers and 14 poster papers from China, India, Korea, Taiwan, and Japan were presented during the three-day symposium. As a result of the review of poster and oral presentations of young scientists by symposium chairs, Dr Kummetha Raghunatha Reddy (Toyota Technological Institute) received the IUMRS-ICA 2008 Young Researcher Award. We are grateful to all invited speakers and many participants for valuable contributions and active discussions. Organizing committee of Symposium (IUMRS-ICA 2008) Professor Toshiji Kanaya (Kyoto University) Professor Kohji Tashiro (Toyota Technological Institute) Professor Kazuo Sakurai(Kitakyushu University) Professor Keiji Tanaka (Kyushu University) Dr Sono Sasaki (JASRI/Spring-8) Professor Naoya Torikai (KENS) Professor Moonhor Ree (POSTECH) Professor Kookheon Char (Seoul National University) Professor Charles C Han (CAS) Professor Atsushi Takahara(Kyushu University) Frontier of Polymeric Nano-Soft-Materials, Precision Polymer Synthesis, Self-assembling and Their Functionalization (Symposium Y of IUMRS-ICA2008) Seiichi Kawahara, Rong-Ming Ho, Hiroshi Jinnai, Masami Kamigaito, Takashi Miyata, Hiroshi Morita, Hideyuki Otsuka, Daewon Sohn, Keiji Tanaka It is our great pleasure and honor to publish peer-reviewed papers, presented in Symposium Y Frontier of Polymeric Nano-Soft-Materials Precision Polymer Synthesis, Self-assembling and Their Functionalization at the International Union of Materials Research Societies International Conference in Asia 2008 (IUMRS-ICA2008), which was held on 9-13 December 2008, at Nagoya Congress Center, Nagoya, Japan. Polymeric nano-soft-materials are novel outcomes based on a recent innovative evolution in polymer science, i.e. precision polymer synthesis, self-assembling and functionalization of multi-component systems. The materials are expected to exhibit specific functions and unique properties due to their hierarchic morphologies brought either by naturally-generated ordering or by artificial manipulation of the systems, e.g., crystallization and phase-separation. The emerging precision synthesis has brought out new types of polymers with well-controlled primary structures. Furthermore, the surface and interface of the material are recognized to play an important role in the outstanding mechanical, electrical and optical properties, which are required for medical and engineering applications. In order to understand structure-property relationships in the nano-soft-materials, it is indispensable to develop novel characterization techniques. Symposium Y aimed to provide recent advances in polymer synthesis, self-assembling processes and morphologies, and functionalization of nano-soft-materials in order to initiate mutual and collaborative research interest that is essential to develop revolutionarily new nano-soft-materials in the decades ahead. Four Keynote lectures, 15 invited talks and 30 posters presented important new discoveries in polymeric nano-soft-materials, precision polymer synthesis, self-assembling and their functionalization. As for the precision polymer synthesis, the latest results were provided for studies on synthesis of polyrotaxane with movable graft chains, organic-inorganic hybridization of polymers, supra-molecular coordination assembly of conjugated polymers, precision polymerization of adamantane-containing monomers, production of high density polymer brush and synthesis of rod coil type polymer. The state-of-the-art results were introduced for the formation of nano-helical-structure of block copolymer containing asymmetric carbon atoms, self-assembling of block copolymers under the electric field, self-assembling of liquid crystalline elastomers, preparation of nano cylinder template films and mesoscopic simulation of phase transition of polymers and so forth. Moreover, recent advantages of three-dimensional electron microtomography and scanning force microscopy were proposed for analyses of nano-structures and properties of polymeric multi-component systems. Syntheses, properties and functions of slide-ring-gel, organic-inorganic hybrid hydrogels, hydrogel nano-particles, liquid-crystalline gels, the self-oscillating gels, and double network gels attracted participants' attention. Modifications of naturally occurring polymeric materials with supercritical carbon dioxide were introduced as a novel technology. Some of the attractive topics are presented in this issue. We are grateful to all the speakers and participants for valuable contributions and active discussions. Organizing committee of Symposium Y (IUMRS-ICA 2008) Chair Seiichi Kawahara (Nagaoka University of Technology, Japan) Vice Chairs Rong-Ming Ho (National Tsing Hua University, Taiwan) Hiroshi Jinnai (Kyoto Institute of Technology, Japan) Masami Kamigaito (Nagoya University, Japan) Takashi Miyata (Kansai University, Japan) Hiroshi Morita (National Institute of Advanced Industrial Science and Technology, Japan) Hideyuki Otsuka (Kyushu University, Japan) Daewon Sohn (Hanyang University, Korea) Keiji Tanaka (Kyushu University, Japan). |
| 218. | F. Ariura, K. Tanaka, T. Nagamura, M. Schappacher, R. Borsali, A. Deffieux, Investigations of Bulk Properties of Comb Polystyrene, 235th ACS National Meeting, Spring 2008 American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 49, 1, 52-53, 2008.09. |
| 219. | T. Date, K. Tanaka, T. Nagamura, T Serizawa, Directional Affinity of Short Peptides for Synthetic Polymers , Chem. Mater. , 20(14), 4536-4538 , 2008.07. |
| 220. | D. Kawaguchi, A. Takano, Y. Matsushita, K. Tanaka, T. Nagamura, N. Torikai, Interdiffusion of Cyclic Polystyrene Whose Molecular Weight is Larger than the Critical Entanglement Molecular Weight, 日本レオロジー学会誌, 10.1678/rheology.36.113, 36, 2, 113-115, 2008.07, [URL], Interdiffusion of cyclic polystyrene (c-hPS) / cyclic deuterated polystyrene (c-dPS) laminated film whose molecular weights are ca.50 k was examined by neutron reflectivity and dynamic secondary ion mass spectroscopy. It has been found that time evolution of the interfacial thicknesses of (c-hPS/c-dPS) multi-layer films are similar to those of the corresponding linear hPS/linear dPS (l-hPS/l-dPS) bilayer films at short time region. However, at the annealing time longer than 5×103 s, the interfacial thicknesses of (c-hPS/c-dPS) multi-layer films are evidently larger than those of the (l-hPS/l-dPS) films at each observing time. These results can be explained in terms of the less entanglement nature of cyclic polymers than that of the linear ones.. |
| 221. | K. Akabori, K. Tanaka, H. Murase, A. Takahara, T. Kajiyama, Model Analysis of Scanning Viscoelasticity Microscopy and Its Applications to Polymer Surfaces, 日本レオロジー学会誌, 10.1678/rheology.36.87, 36, 2, 87-92, 2008.07, [URL], Scanning viscoelasticity microscopy (SVM) with a mechanical model analysis was applied to polystyrene (PS) surfaces. When the surface was in a glassy state, that is, in an elastic regime, the SVM vibrational system can be simply expressed by a series model composed of two springs such as a cantilever and the sample surface. Once the surface reaches in a viscoelastic regime, a damping factor must be incorporated into the model surface. The spring constants for the PS surfaces being in glassy and transition states were successfully extracted by the analysis. The surface value even for the glassy state was lower than the corresponding bulk value by a few decades.. |
| 222. | K. Tanaka, N. Sanada, M. Hikita, T. Nakamura, T. Kajiyama, A. Takahara, Surface Depth Analysis for Fluorinated Block Copolymer Films by X-ray Photoelectron Spectroscopy Using C(60) Cluster Ion Beam, Applied Surface Science, 10.1016/j.apsusc.2008.02.089, 254, 17, 5435-5438, 254(17), 5435-5438, 2008.06, X-ray photoelectron spectroscopy (XPS) using fullerene (C(60)) cluster ion bombardment was applied to films of a fluorinated block copolymer. Spectra so obtained were essentially different from those using Ar ion beam. Structure in the surface region with the depth down to 60 nm drawn on the basis of XPS with C(60) beam was essentially the same as the one drawn by the result using dynamic secondary ion mass spectrometry, which is a well-established method for the depth analysis of polymers. This implies that XPS using C(60) beam enables one to gain access to the depth analysis of structure in polymer. films with the depth range over the analytical depth of conventional XPS, that is, three times inelastic mean-free path of photoelectrons. (c) 2008 Elsevier B.V. All rights reserved.. |
| 223. | 楢山威風, 赤堀敬一, 田中敬二, 長村利彦, 高分子間ナノ接着における発現機構の解明, 日本接着学会年次大会講演要旨集, 46, 79-80, 2008.06. |
| 224. | 赤堀敬一, 田中敬二, 村瀬浩貴, 高原淳, 梶山千里, 走査粘弾性顕微鏡の力学モデル化と高分子表面への応用, 日本レオロジー学会誌, 10.1678/rheology.36.87, 36, 2, 87-92, 36(2), 87-92, 2008.04, Scanning viscoelasticity microscopy (SVM) with a mechanical model analysis was applied to polystyrene (PS) surfaces. When the surface was in a glassy state, that is, in an elastic regime, the SVM vibrational system can be simply expressed by a series model composed of two springs such as a cantilever and the sample surface. Once the surface reaches in a viscoelastic regime, a damping factor must be incorporated into the model surface. The spring constants for the PS surfaces being in glassy and transition states were successfully extracted by the analysis. The surface value even for the glassy state was lower than the corresponding bulk value by a few decades.. |
| 225. | 川口大輔, 高野敦志, 松下裕秀, 田中敬二, 長村利彦, 鳥飼直也, 臨界絡み合い分子量を超える長さを有する環状ポリスチレンの積層膜界面における相互拡散, レオロジー学会誌, 36(2), 113-115, 2008.04. |
| 226. | 田中敬二, 四方俊幸, 表面, 界面および膜特集号に添えて, 日本レオロジー学会誌, 36, 2, 71-71, 2008.04. |
| 227. | H. Sugihara, K. Oya, H. Murase, K. Akabori, K. Tanaka, T. Kajiyama, A. Takahara, Simultaneous Imaging for Surface and Internal Structure of Polymer Blend Thin Films, Applied Surface Science, 10.1016/j.apsusc.2007.10.080, 254, 10, 3180-3183, 254(10), 3180-3183, 2008.03, A novel experimental technique for three-dimensional (3D) visualization of phase-separated structure of polymer blend thin film was proposed. Polystyrene/poly(methyl methacrylate) (PS/PMMA) blend thin films with the thickness of approximately 100 nm were cut at extremely low angle by utilizing surface and interface cutting analysis system (SAICAS), and the cross-section was exposed as gradient surface with the width of approximately 2.5 mu m. SFM investigation for the grazing cross-section imaged the detailed internal and surface phase separated structure of the (PS/PMMA) blend thin films on one image. (c) 2007 Published by Elsevier B.V.. |
| 228. | Y. Fujii, H. Atarashi, T. Nagamura, K. Tanaka, Entanglement Effect on Film Retention of Poly(methyl methacrylate) in Methanol, Chemistry Letters, 10.1246/cl.2008.326, 37, 3, 326-327, 2008.03, [URL], Morphology for films of poly(methyl methacrylate) with various molecular weights was observed before and after methanol immersion by using atomic force microscopy so that the effect of chain entanglement on film retention of a polymer in a liquid can be discussed.. |
| 229. | K. Tanaka, Y. Fujii, H. Atarashi, K. Akabori, M. Hino, T. Nagamura, Nonsolvents Cause Swelling at the Interface with Poly(methyl methacrylate) Films, Langmuir, 10.1021/la702132t, 24, 1, 296-301, 24(1), 296-301, 2008.01, Density profiles of a perdeuterated poly(methyl methacrylate) (dPMMA) film spin-coated on a substrate in water, hexane, and methanol, which are "nonsolvents" for dPMMA, were examined along the direction normal to the interface by specular neutron reflectivity (NR). The interfaces of dPMMA with the liquids were diffuse in comparison with the pristine interface with air; the interfacial width with water was thicker than that with hexane. Interestingly, in water, the dPMMA film was composed of a swollen layer and the interior region, which also contained water, in addition to the diffused layer. The interface of dPMMA with hexane was sharper than that with water. Although there were slight indications of a swollen layer for the dPMMA in hexane, the solvent molecules did not penetrate significantly into the film. On the other hand, in methanol, the whole region of the dPMMA film was strikingly swollen. To conserve mass, the swelling of the film by the nonsolvents is accompanied by an increase in the film thickness. The change in the film thickness estimated by NR was in excellent accord with the results of direct observations using atomic force microscopy (AFM). The modulus of dPMMA in the vicinity of the interfaces with liquids was also examined on the basis of force-distance curves measured by AFM. The modulus decreased closer to the outermost region of the film. The extent to which the modulus decreased in the interfacial region was consistent with the amount of liquid sorbed into the film.. |
| 230. | Y. Fujii, H. Atarashi, N. Yamada, N. Torikai, T. Nagamura, K. Tanaka, Gas Sorption into Surface of Poly(methyl methacrylate) Films at Atmospheric Pressure, Polym. J., 39(12), 1290-1294, 2007.12. |
| 231. | Y. Fujii, K. Akabori, K. Tanaka, T. Nagamura, Chain Conformation Effects on Molecular Motions at the Surface of Poly(methyl methacrylate) Films, Polym. J., 10.1295/polymj.PJ2006270, 39, 9, 928-934, 2007.11, [URL], Surface relaxation in syndiotactic (st-) and isotactic (it-) poly(methyl methacrylate) (PMMA) films was studied by lateral force microscopy. The αa- and β-relaxation processes were clearly observed even at the surface, permitting us to deduce the form of the dispersion map for the surface relaxation processes. Both relaxation temperatures at the surface were lower than the corresponding ones in the bulk. In addition, the extent to which the peak temperature for the surface relaxation processes fell below that of the bulk strongly depended on the stereoregularity of the films. The differences in the chain conformations between the surface and the bulk, which were more remarkable in the st-PMMA, produced this variation in surface mobility.. |
| 232. | Y. Fujii, H. Atarashi, K. Akabori, M. Hino, K. Tanaka, T. Nagamura, Structural Analysis for A Poly(methyl methacrylate) Ultrathin Film in Water by Neutron Reflectivity, J. Phys. Conf. Ser., 83, 012023, 2007.10. |
| 233. | K. Niihara, U. Matsuwaki, N. Torikai, H. Atarashi, K. Tanaka, H. Jinnai, A Novel Structural Analysis for A Cylinder-forming Block Copolymer Thin Film Using Neutron Reflectivity Aided By Transmission Electron Microtomography, Macromolecules, 40(19), 6940-6946, 2007.09. |
| 234. | K. Tanaka, T. Keiko, Study on Nano-physical Properties of Polymer Solids for the Near Future, 高分子, 10.1295/kobunshi.56.38, 56, 1, 2007.09, [URL]. |
| 235. | K. Tanaka, T. Keiko, The Direction of My Future Research in the Field of Polymer Science, 高分子, 10.1295/kobunshi.56.38a, 56, 1, 2007.09, [URL]. |
| 236. | 立石洋平, 赤堀敬一, 田中敬二, 長村利彦, ポリスチレン超薄膜中における階層的分子運動特性, 高分子論文集, 64(7), 429-436, 2007.07. |
| 237. | K. Akabori, K. Tanaka, N. Satomi, T. Nagamura, A. Takahara, T. Kajiyama, Effects of Static and Dynamic Forces on Surface Viscoelastic Response of Polymer Films in Scanning Viscoelasticity Microscopy, Polym. J., 39(7), 684-689, 2007.07. |
| 238. | 岡本泰志, 泉隆夫, 青木孝司, 加藤和夫, 田中敬二, 佐々木園, 高原淳, 梶山千里, ポリブチレンテレフタレートの接着挙動におよぼす熱処理条件の影響, 日本接着学会誌, 43(7), 279-284, 2007.07. |
| 239. | Y. Tateishi, K. Akabori, K. Tanaka, T. Nagamura, Hierarchical Thermal Molecular Motion in Thin Polymer Films, 高分子論文集, 10.1295/koron.64.429, 64, 7, 429-436, 2007.07, [URL], Hierarchical thermal molecular motion was studied in thin films of polystyrene (PS). The segmental motion in the thin films was examined by dynamic mechanical analysis. Molecular motions with a relatively small scale in the thin films were discussed on the basis of the kinetics of photoinduced trans to cis isomerization for azobenzene probes tagged to PS. Apparent glass transition temperatures generally decreased with decreasing film thickness. Although relaxation temperatures of β and γ processes in the thin films would be comparable to those in the bulk, the photoisomerization reaction of azobenzene probes became faster with decreasing thickness. Finally, a model for hierarchical thermal molecular motions in thin films was proposed on the basis of the above-mentioned results.. |
| 240. | Y. Tateishi, K. Tanaka, T. Nagamura, Kinetics of Photoinduced E to Z Isomerization of Azobenzene in Polystyrene Films Thickness, Molecular Weight and Temperature Effects, Journal of Physical Chemistry B, 10.1021/jp0705065, 111, 27, 7761-7766, 2007.07, [URL], E to Z (trans → cis) photoisomerization of azobenzene (Az) chromophores tagged to polystyrene (PS) in thin films was studied as functions of thickness, PS molecular weight, and temperature, using the change in absorption at 336 nm arising from the Az E isomer remaining upon ultraviolet light irradiation at 350 ± 5 nm. The photoisomerization in solid films exhibited fast and slow modes. The fractional amount of the fast mode (I 1) started to increase with decreasing film thickness once the films were thinner than a threshold value. This was explained in terms of a surface layer in which the photoisomerization reaction proceeds quickly, the effect of which becomes more noticeable with decreasing thickness due to a larger surface to volume ratio. The thickness dependence of the I1 fraction was insensitive to the molecular weight of the PS used. The thickness of the surface layer, estimated through a layer model analysis, increased with rising temperature up to 298 K. Interestingly, the surface layer markedly thickened at temperatures at which the molecular motion of PS is on a relatively small scale, namely, at the γ and β relaxation temperatures.. |
| 241. | H. Atarashi, K. Akabori, A. Tanaka, M. Ozawa, K. Tanaka, T. Nagamura, Graft Polymerization Initiated by Photosensitizer Segregated at Surface of Polymer Film Upon Ultraviolet Irradiation, Chemistry Letters, 10.1246/cl.2007.808, 36, 6, 808-809, 2007.06, [URL], A novel approach to surface modification of polymer films is proposed on the basis of graft polymerization initiated from photosensitizers attached to hyperbranched polymers which are localized at the film surface.. |
| 242. | D. Kawaguchi, K. Tanaka, N. Torikai, A. Takahara, T. Kajiyama, Surface and Interfacial Segregation in Blends of Polystyrene with Functional end Groups and Deuterated Polystyrene, Langmuir, 10.1021/la700418j, 23, 13, 7269-7275, 2007.06, The effect of chain-end chemistry on surface and interfacial segregation in symmetric blends of polystyrene (hPS)/deuterated polystyrene (dPS) has been investigated by X-ray photoelectron and secondary ion mass spectroscopy in conjunction with neutron reflectivity measurements. alpha,omega-Fluoroalkyl- and alpha,omega-carboxy-terminated polystyrenes (alpha,omega-hPS(R(f))(2) and alpha,omega-hPS(COOH)(2)) were used as end-functionalized polymers; the former possesses chain ends with lower surface energies, and the latter possesses higher surface energies compared with that of the main chain. In the case of an alpha,omega-hPS(R(f))(2)/dPS blend film, alpha,omega-hPS(R(f))(2) was enriched at the surface owing to the surface localization of the R(f) groups, although the surface energy of the hPS segments was slightly higher than that of the dPS ones. On the contrary, in the case of an alpha,omega-hPS(COOH)(2)/dPS blend film, dPS was preferentially segregated at the surface. This may be due to a surface depletion of COOH ends and an apparent molecular weight increase of alpha,omega-hPS(COOH)(2) produced by a hydrogen-bonded intermolecular association of COOH ends in addition to the surface energy difference between hPS and dPS segments. Interestingly, both R(f) and COOH chain ends were partitioned to the substrate interface for the alpha,omega-hPS(R(f))(2)/dPS and alpha,omega-hPS(COOH)(2)/dPS blend films, resulting in the segregation of the hPS component at the substrate interface for both blends. The results presented imply that surface and interfacial segregation in polymer blends could be regulated by incorporating functional groups into the end portions of one component.. |
| 243. | H. Atarashi, F. Ariura, K. Akabori, A. Tanaka, M. Ozawa, K. Tanaka, T. Nagamura, Interfacial Segregation of Hyper-branched Polystyrene in Mixtures of Linear Component, Trans. Mater. Res. Soc. Japan, 32(1), 231-234, 2007.04. |
| 244. | Y. Fujii, Hironori A., N. Yamada, N. Torikai, K. Tanaka, T. Nagamura, Interfacial Structure of Deuterated Poly(methyl Methacrylate) with Carbon Dioxide below the Bulk Glass Transition Temperature, Trans. Mater. Res. Soc. Japan, 32(1), 293-296, 2007.04. |
| 245. | K. Akabori, K. Tanaka, A. Takahara, T. Kajiyama, T. Nagamura, Substrate Effect on Mechanical Relaxation of Polystyrene in Ultrathin Films, J.Phys. IV France, 投稿中, 2007.02. |
| 246. | K. Akabori, K. Tanaka, T. Nagamura, A. Takahara, T. Kajiyama, Thermal Molecular Motion in Polystyrene Thin and Ultrathin Films by Dynamic Viscoelastic Measurement, Journal of Central South University of Technology (English Edition), 10.1007/s11771-007-0279-6, 14, 1 SUPPL., 346-349, 2007.02, [URL], Segmental motion in polystyrene (PS) thin and ultrathin films supported on substrates was studied by dynamic viscoelastic measurement. A polymer film, which has the thickness comparable to or less than twice of radius of gyration of an unperturbed chain (2R g), is defined as an ultrathin film. In the case of PS, α a-relaxation process corresponding to the segmental motion was generally observed at approximately 380 K. Even for both the PS thin and ultrathin films, the α a-absorption peak was clearly observed. A rheological analysis reveals that the α a-relaxation behavior for the thin films with the thickness of about 200 nm is the same as that of the bulk sample. On the contrary, in the case of the PS ultrathin films, the α a-absorption peak on temperature-loss modulus (E) curve is broadened toward both lower and higher temperature sides. This can be interpreted by taking into account that the segmental motion in the vicinity of surface and interface is detectable for such ultrathin films, which should be faster and slower than that in the bulk, respectively. And, it is found that the apparent activation energy (ΔH) for the α a-relaxation in the ultrathin films becomes smaller than the bulk value probably due to the surface effect. Finally, an interfacial effect on the ΔH was studied by using different substrates. When the interaction between PS and substrate becomes stronger, the ΔH value for the α a-relaxation in the ultrathin films increases. The results imply that the segmental motion in the polymer ultrathin films is strongly influenced by surface and interfacial effects.. |
| 247. | T. Aoki, Y. Okamoto, T. Izumi, K. Kato, K. Tanaka, A. Takahara, T. Kajiyama, A Fundamental Study of Adhesive Reliability-A Study of PBT-Epoxy Adhesive Interface-, Rev Automot Eng, 28, 1, 73-79, 2007.01. |
| 248. | N. Sato, T. Yamamoto, Y. Iwasaki, K. Kato, M. Yoshikawa, Y. Hirasawa, M. Kamiya, K. Murai, T. Takano, K. Tanaka, Important Factors for the Prevention of Renal Function Under the Inhibition of Rennin-Angiotensin-Aldosterone System in Acute Heart Failure, Journal of Cardiac Failure, 10.1016/j.cardfail.2006.08.171, 12, 8, S179-S179, 2006.10. |
| 249. | H. Morita, K. Tanaka, T. Kajiyama, T. Nishi, M. Doi, Study of the Glass Transition Temperature of Polymer Surface by Coarse-Grained Molecular Dynamics Simulation, Macromolecules, 10.1021/ma052632h, 39, 18, 6233-6237, 2006.09, [URL], The glass transition temperature at the surface of polymer film is studied by the coarse-grained molecular dynamics simulation. By the analysis of the segmental motion, the glass transition temperatures at the surface region and that in the bulk region are determined separately. The glass transition at the surface region is found to be lower than that in the bulk region. The molecular weight dependence of the glass transition temperature obtained by the simulation agrees well with that obtained by the scanning force microscopic measurements.. |
| 250. | Y. Okamoto, K. Kato, T. Aoki, T. Izumi, K. Tanaka, A. Takahara, T. Kajiyama, Influence of Plasma Treatment on Adhesion Behavior of Poly(butylene terephthalate), 55th Society of Polymer Science Japan Symposium on Macromolecules 55th SPSJ Symposium on Macromolecules, 55, 3442, 2006.09, An effect of surface treatment on adhesion behavior of poly (butylene terephthalate) (PBT) with epoxy adhesive was studied. In general, PBT is annealed at a temperature above the glass transition temperature to obtain dimensional stability for the practical use. However, such an annealing procedure makes the adhesion properties poorer. In this study, we demonstrate that tensile adhesive strength for annealed PBT could be improved through plasma treatment. Tensile adhesive strength increased with increasing surface density of C-O and COO groups, which were quantitatively detected by XPS. Finally, it was concluded that chemical interaction between carboxyl and/or ester groups of PBT and hydroxyl groups of epoxy adhesive was a responsible factor in improving adhesive strength between PBT and epoxy adhesive.. |
| 251. | K. Oya, K. Akabori, H. Murase, K. Tanaka, A. Takahara, T. Kajiyama, Nano-rheological Analysis of Polymer Thin Films Prepared by Gradient Shaving Method, 55th Society of Polymer Science Japan Symposium on Macromolecules 55th SPSJ Symposium on Macromolecules, 55, 3095-3096, 2006.09, In order to investigate structure of diblock copolymer thin film, gradient shaved surface was prepared by using Surface And Interfacial Cutting Analysis System (SAICAS). The scanning viscoelasticity microscopic observation of sliced film revealed the alternate lamellar structures with different mechanical properties in the depth direction.. |
| 252. | K. Akabori, D. Baba, K. Koguchi, K. Tanaka, T. Nagamura, Relation Between the Adhesion Strength and Interfacial Width for Symmetric Polystyrene Bilayers, J.Polym. Sci. B: Polym. Phys., 印刷中, 2006.08. |
| 253. | D. Kawaguchi, K. Masuoka, A. Takano, K. Tanaka, T. Nagamura, N. Torikai, R. M. Dalgliesh, S. Langridge, Y. Matsushita, Comparison of Interdiffusion Behavior Between Cyclic and Linear Polystyrenes with High Molecular Weights, Macromolecules, 10.1021/ma060652t, 39, 16, 5180-5182, 2006.08, [URL], The interdiffusion behavior between cyclic and linear polystyrenes with high molecular weight based on dynamic secondary ion mass spectroscopy (DSIMS) in conjunction with neutron reflectivity (NR) measurements was investigated. Polymers used in this study are monodisperse cyclic and linear PSs (c-hPS, 1-hPS) and those deuterated counterparts (c-dPS, 1-dPS). Time evolution of interfacial thickness with annealing was evaluated by NR and DSIMS. The broadening of the (c-hPS/c-dPS) interface takes place much more rapidly than that of corresponding linear ones. The diffusion of cyclic polystyrene is much faster than that of linear polystyrene. Both thickness of (c-hPS/c-dPS) and (1-hPS/1-dPS) interfaces increase with increasing temperature at 120°C, and that of (c-hPS/c-dPS) bilayer films is much higher than that of (1-hPS/1-dPS) ones at any given temperature.. |
| 254. | M. Hino, M. Kitaguchi, H. Hayashida, Y. Kawabata, S. Tasaki, T. Ebisawa, D. Yamazaki, R. Maruyama, K. Tanaka, N. Torikai, R. Inoue, T. Kanaya, A Test of MIEZE-Reflectometer for Study of Surface and Interface, Physica B, 印刷中, 2006.07. |
| 255. | K. Tanaka, Photo-induced Phenomena in Chalcogenide Glass: Comparison with Those in Oxide Glass and Polymer, Journal of Non-Crystalline Solids, 10.1016/j.jnoncrysol.2006.02.070, 352, 23-25, 2580-2584, 2006.07, Two topics, the both being related with localized states in non-crystalline solids, are studied. One is a comparison of photo-induced phenomena in oxide, chalcogenide, and organic materials. Despite of different inorganic and organic structures, there exist many similarities in photo-induced phenomena, which can be ascribed to excitation of localized electronic states. The other topic concerns photo-induced phenomena induced by linear and non-linear excitation. A result on As2S3 demonstrates that band-gap excitation by one- and two-photon processes provides different changes. It is suggested that the two-photon process occurs resonantly at around localized states in amorphous materials, and the process plays important roles in the structural change. (c) 2006 Elsevier B.V. All rights reserved.. |
| 256. | 繁野雅次, 古川一暁, 田中敬二, 生命の世界・視えるものと観たいもの : 生体計測・SPMの可能性, 應用物理, 75, 6, 758-759, 2006.06. |
| 257. | D. Kawaguchi, A. Takano, Y. Matsushita, N. Torikai, K. Tanaka, T. Nagamura, R. Dalgliesh, S. Langridge, Comparison of Molecular Motion Between Linear Polystyrenes and Cyclic Polystyrenes with Same Molecular Weight, 55th Society of Polymer Science Japan Symposium on Macromolecules 55th SPSJ Symposium on Macromolecules, 55, 3131-3132, 2006.05, Time evolution of interfacial thicknesses between a cyclic polystyrene (c-hPS) / its deuterated counterpart (c-dPS) and a linear polystyrene (1-hPS) / its deuterated counterpart (1-dPS) bilayer films was investigated by dynamic secondary ion mass spectrometry (DSIMS) and neutron reflectivity (NR). The interfacial thickness of (c-hPS/c-dPS) film was significantly larger than that of (1-hPS/1-dPS) film at any given annealing time, indicating that the diffusion constant of c-PS is constantly larger than that of 1-PS. It might be explained that weaker topological constraint comes from the entanglement for the c-PS than for the 1-PS.. |
| 258. | Y. Okamoto, K. Kato, T. Aoki, T. Izumi, K. Tanaka, O. Sakata, A. Takahara, T. Kajiyama, Effect of Annealing Treatment and Surface Treatment on Adhesion Behavior of Poly(Butylene Terephthalate), 55th SPSJ Annual Meeting Polymer Preprints, Japan - 55th SPSJ Annual Meeting, 55, 1136, 2006.05, Influence of annealing treatment on adhesion behavior of poly(butylene terephthalate) (PBT) with epoxy adhesive was studied. The tensile adhesion strength decreased after the annealing treatment of PBT. In the case of the untreated PBT, the failure depth after the failure was not clearly defined. Once the PBT was annealed, the average failure depth turned to be 4 nm. The above results imply that the failure mechanism for the system transformed from interfacial failure to cohesive fracture upon annealing treatment. This can be easily understood by taking into account that a mechanically weak layer is formed in the surface region of PBT after the annealing. Such a weak boundary layer was observed by scanning viscoelasticity microscopy. Improvement of adhesive property was confirmed by surface treatment.. |
| 259. | K. Akabori, K. Oya, H. Murase, K. Tanaka, A. Takahara, T. Kajiyama, Nano-rheological Analysis of Polymer Cross-Section Films Prepared by a Mechanical Cutting Method, 55th SPSJ Annual Meeting Polymer Preprints, Japan - 55th SPSJ Annual Meeting, 55, 1270, 2006.05, A cross-section film of a symmetric diblock copolymer, in which lamellar structure was formed, was successfully prepared by a mechanical cutting method using a sharp diamond knife. In this method, the knife was obliquely pushed into the sample from the surface side. The oblique angle was precisely controlled to be 0.57 deg. Thus, periodic lamellar structure was shown up at the surface of the cross-section film Then, scanning viscoelasticity microscopy (SVM), which can image viscoelastic information at the surface, was applied to the cross-section film. Finally, it was demonstrated that a combination of SVM and mechanical cutting method enabled one to gain direct insight into the depth information for structure and physical properties of the diblock copolymer film along the direction normal to the surface.. |
| 260. | 田中敬二, 束縛場における高分子のガラス転移, 高分子論文集, 63:539-547, 2006.01. |
| 261. | K. Tanaka, Y. Tshchimura, K. Akabori, F. Ito, T. Nagamura, Time-and Space-resolved Fluorescene Study on Interfacial Mobility of Polymers, Appl. Phys. Lett., 89:061919-1-2, 2006.01. |
| 262. | T. Koga, S. Yasutake, K. Tanaka, K. Akabori, K. Andou, T. Kajiyama, A. Takahara, Evaluation of Surface Mechanical Properties of Organic Ultrathin Films Using Scanning Force Microscope, 54th SPSJ Symposium on Macromolecules 54th SPSJ Symposium on Macromolecules - Polymer Preprints, Japan, 54, 3840-3841, 2005.12, Surface mechanical properties of polystyrene (PS) film prepared from single droplet of PS solution by ink-jet (IJ) method, and [PS / Polybutadiene (BDA)] (60/40, w/w) blend film were investigated by scanning force microscope. The scanning viscoelesticity microscopic measurements at various temperatures clarified that the relative difference of contrast of the PS and the PBD phase surface becomes small with an increase of temperature. This is due to the relative difference of elasticity of PS and PBD phases. Based on the temperature dependent lateral force measurements, the surface of the PS film prepared by IJ method was in a glass-rubber transition state even at 343 K, in spite of that the bulk Tg was far above 343 K [Tg (bulk)=378 K]. Similar temperature dependence of lateral force was also observed on the PS film prepared by spin-coating method.. |
| 263. | M. Hikita, K. Tanaka, T. Nakamura, T. Kajiyama, A. Takahara, Super Liquid Repellent Surfaces Prepared by Colloidal Silica Nano-Particles Covered with Fluoroalkyl Groups, Laugmuir, 10.1021/la050901r, 21, 16, 7299-7302, 21:7299-7302, 2005.08. |
| 264. | Y. Okamoto, K. Kato, T. Aoki, T. Izumi, K. Tanaka, O. Sakata, S. Sasaki, A. Takahara, T. Kajiyanm, An Effect of Surface Treatment on Adhesion Behavior of Poly (butylene terephthalate), 54th SPSJ Symposium on Macromolecules 54th SPSJ Symposium on Macromolecules - Polymer Preprints, Japan, 54, 3289-3290, 2005.05, An effect of surface treatment on adhesion behavior of poly (butylene terephthalate) (PBT) with epoxy adhesive was studied. In general, PBT is supposed to be annealed at a temperature above the glass transition temperature to obtain dimensional stability for the practical use. However, such an annealing procedure makes the adhesion properties poorer. In this study, we demonstrate that tensile adhesive strength for annealed PBT could be improved through UV irradiation or chemical etching treatment. Tensile adhesive strength increased with increasing surface density of C-O and C=O groups, which were quantitatively detected by XPS. Finally, it was concluded that chemical interaction between carboxyl and/or ester groups of PBT and hydroxyl groups of epoxy adhesive was a responsible factor in improving adhesive strength between PBT and epoxy adhesive.. |
| 265. | K. Aoi, T. Fukui, Y. Otsuka, K. Tanaka, T. Nagamura, Architecture and Shape Control of Nanoobjects Based on Amphiphilic Dendrimers, 54th SPSJ Symposium on Macromolecules 54th SPSJ Symposium on Macromolecules - Polymer Preprints, Japan, 54, 2715-2716, 2005.05, In the field of nanotechnology and nanoscience, dendrimers are key compounds having well-defined chemical structure. We nave already reported synthesis of globular carbohydrate macro molecule "sugar ball" which is applicable to gene and drug carriers [1-4]. Amphiphilic surface-sugar- substituted surface-block dendrimers have been also designed, synthesized and characterized [4]. Supramolecular architeucture based on amphiphilic dendrimers is important to create shape controlled smart nanoobjects[5]. The present report deals with synthesis and assembly of amphiphilic sugar-substituted poly(ethylene glycol) dendrimers. The dendrimers were synthesized by the reaction of N-acetyl-D-glucosamine, galactose, and lactose derivatives with poly(ethylene glycol) dendrimer having a hydroxy group and alkyl groups at the core and the surface, respectively, wnich were prepared by convergent method. The sugar moieties and the poly(ethylene glycol) dendrimer branches are regarded as hydrophilic parts, whereas the alkyl groups act as hydrophobic groups. Although hydrophobicity of the amphiphilic dendrimers is high, nanoparticles based on the amphiphilic dendrimers can be prepared by irradiation of ultrasonic wave. Fortunately the particle size, which is measured using DLS, could be controlled around ca. 200 nm. Monolayer of the amphiphilic dendrimers was successfully formed at the air/water interface. Intermolecular distance, i.e., intersugar distance, of the monolayer was found to be controlled around 2 nm by changing generation and hydrophobic groups of the dendrimers.. |
| 266. | K. Akabori, K. Tanaka, T. Nagamura, A. Takahara, T. Kajiyama, Effect of Substrate Interface on Mechanical Relaxation Behavior in Polymer Ultrathin Films, 54th SPSJ Annual Meeting 2005 54th SPSJ Annual Meeting 2005 - Polymer Preprints, Japan, 54, 925, 2005.05, Mechanical relaxation behavior of polystyrene (PS) and poly (2-vinylprydine) (P2VP) thin and ultrathin films on substrates was examined. Even in the case of the ultrathin films, the α2-relaxation process corresponding to the segmental motion was successfully observed. However, the αa-absorption peak was broadened toward lower and higher temperature sides because of surface and interfacial effects. Interestingly, when a PS ultrathin film was sandwiched between SiOx layers, an additional peak come up with the interfacial segmental motion appeared at the higher temperature side. In the case of the P2VP ultrathin films on the SiOx substrates, the interfacial effect became remarkable due to the strong attractive interaction between chains and the substrate. Finally, it was concluded that chain mobility in the interfacial region was depressed in comparison with that in the internal bulk phase.. |
| 267. | Y. Okamoto, K. Kato, T. Izumi, K. Tanaka, O. Sakata, A. Takahara, T. Kajiyama, Influence of Annealing Treatment on Adhesion Behavior of Poly(butylene terephthalate), 54th SPSJ Annual Meeting 2005 54th SPSJ Annual Meeting 2005 - Polymer Preprints, Japan, 54, 879, 2005.05, Influence of annealing treatment on adhesion behavior of poly(butylene terephthalate) (PBT) with epoxy adhesive was studied. The tensile adhesion strength decreased after the annealing treatment of PBT. In the case of the untreated PBT, the failure depth after the failure was not clearly defined. Once the PBT was annealed, the average failure depth turned to be 4 nm. The above results imply that the failure mechanism for the system transformed from interfacial failure to cohesive fracture upon annealing treatment. This can be easily understood by taking into account that a mechanically weak layer is formed in the surface region of PBT after the annealing. Such a weak boundary layer was observed by grazing incidence X-ray diffraction measurement.. |
| 268. | M. Hikita, T. Nakamura, K. Tanaka, A. Takahara, T. Kajiyama, Super-water-repellent Coating on Polymer Substrates Using Fluorosilane-silica Hybrid Materials, 54th SPSJ Annual Meeting 2005 - Polymer Preprints, Japan, 54, 1573, 2005.05, The purpose of this study is to develop transparent super-water-repellent surfaces with a simple way and to apply this coating to polymer substrates. Super-water-repellent surfaces are generally made by controlling chemistry and roughness at the surface. In this study, surface roughness was controlled by the content of colloidal silica particles in a sol-gel thin film covered with fluoroalkyl silane coupling agent. When the fractional amount of colloidal silica was in the range of 10-30 wt%, root mean square roughness at the surface by AFM was around 30-70 nm. X-ray photoelectron spectroscopy revealed that these surfaces were covered with fluoroalkyl groups. Consequently, these surfaces exhibit excellent water repellencies such as contact angles of 150 deg. to water. This coating procedure can be applied to transparent polymer substrates such as poly(ethyleneterephtarate) (PET) films. In that case, transparency and durability of the sol-gel layer on the PET film are sufficient enough to be applied for practical use.. |
| 269. | H. Yokoyama, T. Miyamae, S. Han, T. Ishizone, A. Takahara, K. Tanaka, N. Torikai, Surface Segregation of Watersoluble-Hydrophobic Block Copolymers, 54th SPSJ Annual Meeting 2005 54th SPSJ Annual Meeting 2005 - Polymer Preprints, Japan, 54, 974, 2005.05, A block copolymer of deuterated polystyrene (dPS) and 2-[2-(2- methoxyethoxy)ethoxy]ethyl methacrylate (PME3MA) spontaneously exposes the PME3MA block, which is soluble in water, to the surface in a vacuum. dPS-PME3MA mixed with polystyrene (PS) segregates to the PS surface spontaneously and changes the hydrophobic PS surface into hydrophilic surface. The detail of the segregation will be discussed.. |
| 270. | T. Kajiyama, K. Tanaka, A. Takahara, S. Sasaki, Establishment of How to Analyze Molecular Motion for Polymer Chains at Surface and Interfaces, Annu Rep Fac Eng Kyushu Univ, 2004, 10-17, 2005.05. |
| 271. | A. Sakai, K. Tanaka, Y. Fujii, T. Nagamura, T. Kajiyama, Structure and Thermal Molecular Motion at Surface of Semi-Crystalline Isotactic Polypropylene Films, Polymer, 10.1016/j.polymer.2004.11.021, 46, 2, 429-437, 46:429-437, 2005.01. |
| 272. | H. Yakabe, K. Tanaka, T. Nagamura, S. Sasaki, O. Sakata, A. Takahara, T. Kajiyama, Grazing Incidence X-ray Diffraction Study on Surface Crystal Structure of Polyethylene Thin Films, Polym. Bull., 10.1007/s00289-004-0329-2, 53, 3, 213-222, 53:213-222, 2005.01. |
| 273. | H. Yokoyama, T. Miyamae, S. Han, T. Ishizone, K. Tanaka, A. Takahara, N. Torikai, Spontaneously Formed Hydrophilic Surfaces by Segregation of Block Copolymers with Water-Soluble Blocks, Macromolecules, 10.1021/ma050473w, 38, 12, 5180-5189, 38:5180-5189, 2005.01. |
| 274. | 疋田真也、田中敬二、中村哲也、高原淳、梶山千里, フッ素−シリカハイブリッドコーティングによる透明超撥水表面の形成, 表面科学, 26:559-563, 2005.01. |
| 275. | 中原重樹、本岡正則、田中敬二、高原淳、梶山千里, 走査プローブ顕微鏡による(ポリプロピレン/エラストマー粒子)系ブレンド界面の評価, 高分子論文集, 62:432-434, 2005.01. |
| 276. | K. Akabori, K. Tanaka, T. Nagamura, A. Takahara, T. Kajiyama, Molecular Motion in Ultrathin Polystyrene Films: Dynamic Mechanical Analysis of Surface and Interfacial Effects, Macromolecules, 10.1021/ma051143e, 38, 23, 9735-9741, 38:9735-9741, 2005.01. |
| 277. | S. Nakahara, M. Motowoka, K. Tanaka, A. Takahara, T. Kajiyama, Evaluation of Interfacial Structure in Blends of Polypropylene and Elastomer by Scanning Force Mircroscopy, 高分子論文集, 10.1295/koron.62.432, 62, 9, 432-434, 2005.01, [URL], Flat cross-sections of (polypropylene/elastomer) blends were prepared by ultamicrotoming at 150 K. Then, scanning force microscopy (SFM) was applied to each cross-section to evaluate the interfacial thickness between the two phases in the blend. For this purpose, a viscoelastic mode was superior to a conventional topographic mode. The results obtained well reflected the solubility between the two components. Finally, transmission electron microscopy was applied to the sample. The TEM observations supported what was suggested on the basis of SFM results.. |
| 278. | T. Kajiyama, K. Kojio, K. Tanaka, Aggregation States and Molecular Motion of Polymer Ultrathin Films Prepared at the Air/water Interface, Advances in Colloid and Interface Science, 10.1016/j.cis.2004.09.007, 111, 3 SPEC. ISS., 159-179, 2004.12, [URL], The preparation of poly(amido amine) (PAMAM) dendrimer monolayers at the air/water interface was analyzed. Investigations show the transfer of PAMAM dedrimer monolayers from the air side onto hydrophobic silicon wafers, which were treated by the horizontal lifting method. X-ray reflectivity, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques were used to study the aggregation states in the PAMAM monolayers. The results show that the PAMAM molecules sit on the substrate with an oblate shape in which the hydrophilic core and hydrophobic alkyl end groups were towards the substrate and air sides.. |
| 279. | K. Tanaka, Study on Surface Glass Transition Behavior in Monodisperse Polystyrene Films, 日本レオロジー学会誌, 10.1678/rheology.32.17, 32, 1, 17-25, 2004.05, [URL], Surfaces in polymeric materials play an important role in many technological applications. Hence, systematical understanding of aggregation states and physical properties at the surfaces is of pivotal importance as the first benchmark so that highly functionalized polymeric materials based on surface peculiarity can be promisingly designed and constructed. Nevertheless, surface properties, especially rheological properties, had not been studied until early 90s because of technical difficulties. In 1993, we started to embark on this intriguing and challenging issue by mainly scanning force microscopy using monodisperse polystyrene (PS) solid films. Consequently, conclusions obtained thus far are consistently arrived that molecular motion at the PS surfaces is thermally activated in comparison with the corresponding internal bulk region. However, it is far from clear for the moment what the whole picture of such peculiar surface mobility is, although we believe that some parts of it have been successfully clarified to date. Here, experimental methods to examine surface rheological properties, which we have proposed, are mentioned at first, and then, essential points of what we have established are discussed.. |
| 280. | N. Hosaka, K. Tanaka, H. Otsuka, A. Takahara, Dewetting Behavior of Polymer Thin Film with octacyclopentylsilsesquioxane Nanofiller, Abstracts of Papers of THE American Chemical Society, 227, U834-U834, 2004.03. |
| 281. | M. Hikita, N. Takizuka, K. Tanaka, A. Takahara, T. Kajiyama, Characterizations and Surface Wettability of Fluorinated Block Copolymers Synthesized by Atom Transfer Radical Polymerization, Trans Mater Res Soc Jpn, 29, 1, 225-228, 2004.02. |
| 282. | T. Izumi, R. Narita, K. Tanaka, A. Takahara, T. Kajiyama, Influence of Annealing Treatment on the Adhesion of Poly(butylene terephthalate) and Its Interfacial Structure, Trans Mater Res Soc Jpn, 29, 1, 229-232, 2004.02. |
| 283. | K. Akabori, K. Tanaka, T. Nagamura, A. Takahara, T. Kajiyama, Segmental Motion in Polystyrene Thin and Ultrathin Films Based on Dynamic Viscoelastic Measurement, Trans Mater Res Soc Jpn, 29, 1, 217-220, 2004.02. |
| 284. | H. Yokoyama, K. Tanaka, A. Takahara, T. Kajiyama, K. Sugiyama, A. Hirao, Surface Segregation of Fluoroalkyl Side Group of Fluorinated Block Copolymers, Trans Mater Res Soc Jpn, 29, 1, 279-282, 2004.02. |
| 285. | T. Kajiyama, K. Tanaka, A. Takahara, Analysis of Surface Mobility in Polystyrene Films with Monodisperse and Bimodal Molecular Weights by Lateral Force Microscopy, J. Polym. Sci. Part A: Polym. Chem., 10.1002/pola.10873, 42, 3, 639-647, 42:639-647, 2004.01. |
| 286. | H. Yokoyama, K. Tanaka, A. Takahara, T. Kajiyama, K. Sugiyama, A. Hirao, Surface Structure of Asymmetric Fluorinated Block Copolymers: Poly[styrene-block-4-(perfluorooctylpropyloxy)styrene], Macromolecules, 10.1021/ma035191f, 37, 3, 939-945, 37:939-945, 2004.01. |
| 287. | K. Tanaka, F. Ariura, T. Nagamura, T. Kajiyama, Further Study of Chain End Effect on Surface Mobility in Monodisperse Polystyrene Films, Polym. J., 10.1295/polymj.36.498, 36, 6, 498-501, 36:498-501, 2004.01. |
| 288. | M. Hikita, K. Tanaka, T. Nagamura, T. Kajiyama, Aggregation States and Surface Wettability in Films of Poly(styrene-block-2-perfluooctyl ethyl acrylate)Diblock Copolymers Synthesized by Atom Transfer Radical Polymerization, Langmuir, 10.1021/la049556g, 20, 13, 5304-5310, 20:5304-5310, 2004.01. |
| 289. | N. Hosaka, K. Tanaka, H. Otsuka, A. Takahara,, Influence of the Addition of Silsesquioxane on the Dewetting Behavior of Polystyrene Thin Film, Compos. Interface., 10.1163/1568554041738157, 11, 4, 297-306, 11:297-306, 2004.01. |
| 290. | T. Izumi, K. Tanaka, R. Narita, S. Horiuchi, A. Takahara, T. Kajiyama, Annealing Effect on Adhesion Properties of Poly(butylene Terephthalate), Compos. Interface., 10.1163/1568554041738166, 11, 4, 325-333, 11:325-333, 2004.01. |
| 291. | K. Tanaka, Y. Tateishi, T. Nagamura, Photoisomerization of Azobenzene Probes Tagged to Polystyrene in Thin Films, Macromolecules, 10.1021/ma048579z, 37, 22, 8188-8190, 37:8188-8190, 2004.01. |
| 292. | D. Kawaguchi, K. Tanaka, T. Kajiyama, A. Takahara, S. Tasaki, Surface Composition Control via Chain end Segregation in Blend Films of Polystyrene and Poly(vinyl methyl ether), Macromolecules, 10.1021/ma034117u, 36, 18, 6824-6830, 36 (18): 6824-6830, 2003.09, Surface aggregation states in miscible blends of monodisperse polystyrene (PS) and poly(vinyl methyl ether) (PVME) were studied by X-ray photoelectron spectroscopy (XPS) in conjunction with neutron reflectivity (NR). In the case of symmetric blends in terms of degree of polymerization, N, PVME and PS were preferentially segregated at the film surface and the interface with a silicon wafer, respectively, to minimize free energy of the system. The concentration profile near the surface obtained by experiments was consistent with a mean-field prediction. Also, the surface composition in symmetric blends composed of PS terminated by fluoroalkyl groups at both ends (a,omega-PS(R-f)(2)) and PVME was examined. In this case, the surface enrichment of PVME was suppressed by virtue of the surface localization of fluoroalkyl end groups, and the composition was strongly dependent on N. The surface in asymmetric alpha,omega-PS(R-f)(2)/PVME blend, in which N of alpha,omega-PS(R-f)(2) was much smaller than that of PVME, was mostly covered with the PS segments. The results presented imply a possibility that the surface composition in miscible polymer mixtures could be perfectly regulated combining the chain end effect with the molecular weight disparity between the components.. |
| 293. | T. Kajiyama, D. Kawaguchi, K. Tanaka, Surface Mobility in Monodisperse Polystyrene Films, Macromolecular Symposia, 10.1002/masy.200351111, 201, 95-102, 2003.09, [URL], Surface dynamics in monodisperse polystyrene films was examined by lateral force microscopy in conjunction with dynamic secondary ion mass spectroscopy. Glass transition temperature, Tg, at the surface was markedly lower than the corresponding bulk Tg. Also, it was shown that polymer chains present at the surface could diffuse even at a temperature below the bulk Tg. The surface depth, in which molecular motion was activated, was of the order of 5 nm.. |
| 294. | K. Tanaka, K. Hashimoto, T. Kajiyama, A. Takahara, Visualization of Active Surface Molecular Motion in Polystyrene Film by Scanning Viscoelasticity Microscopy, Langmuir, 10.1021/la034542g, 19, 17, 6573-6575, 19 (17): 6573-6575, 2003.08, A monodisperse polystyrene (PS) film was spin-coated on a silicon wafer with native oxide layer and was in part scratched by a blade. Then, the surface modulus on a given area, in which PS and bared silicon were present, was two-dimensionally mapped as a function of temperature by scanning viscoelasticity microscopy. We visually present evidence that the PS surface started to soften up at a temperature much lower than the bulk glass transition temperature.. |
| 295. | K. Akabori, K. Tanaka, T. Kajiyama, A. Takahara, Anomalous Surface Relaxation Process in Polystyrene Ultrathin Films, Macromolecules, 10.1021/ma034001y, 36, 13, 4937-4943, 36 (13): 4937-4943, 2003.07, Monodisperse polystyrene (PS) films with various thicknesses were spun-coated on silicon wafers with native oxide layer. Surface relaxation behavior in the PS films was studied as a function of thickness by lateral force microscopy (LFM). In the case of a thick PS film, a clear lateral force peak corresponding to surface alpha(a)-relaxation process of segmental motion was observed at a temperature much lower than the bulk glass transition temperature, T-g. As the film became thinner than 3-4 times the radius of gyration of an unperturbed consistent chain, the peak on lateral force vs temperature curve started to broaden out with decreasing thickness and eventually split into two peaks. The appearance temperature of the surface a alpha(a)-relaxation peak was invariant with respect to the film thickness even in such an ultrathin state, meaning that surface T-g was insensitive to the thickness. On the other hand, the ultrathinning-induced relaxation process, called surface beta-relaxation, was strongly dependent on the thickness in terms of relaxation temperature and apparent activation energy. Finally, possible origins of the surface beta-relaxation process were proposed.. |
| 296. | K. Tanaka, D. Kawaguchi, Y. Yokoe, T. Kajiyama, A. Takahara, S. Tasaki, Surface Segregation of Chain ends in Alpha, Omega-Fluoroalkyl-Terminated Polystyrenes Films, Polymer, 10.1016/S0032-3861(03)00391-4, 44, 15, 4171-4177, 2003.07, alpha,omega-Fluoroalkyl-terminated polystyrenes (alpha,omega-PS(R-f)(2)) with various molecular weights were synthesized by an anionic polymerization. Then, chain end distribution in the surface region of the alpha,omega-PS(R-f)(2) films was studied by angular-dependent X-ray photoelectron spectroscopy in conjunction with neutron reflectivity. The alpha,omega-PS(R-f)(2) films annealed under vacuum exhibited surface localization of chain ends. Since the fluoroalkyl chain ends possess a lower surface free energy compared with the main chain part, they energetically prefer to partition to the surface. The extent to which the chain ends were segregated at the surface was examined as a function of molecular weight. Also, it was presented how surface orientation of the fluoroalkyl end groups was dependent on molecular weight. On the other hand, no segregation of the chain ends was observed at the surface of the alpha,omega-PS(R-f)(2) film annealed in boiled water. This is because the chain ends with a lower surface free energy tend to stay away from the higher energy medium of the boiled water. This result reveals that the surface concentration of chain ends can be regulated by selecting an appropriate annealing condition based on surface thermodynamics. (C) 2003 Elsevier Science Ltd. All rights reserved.. |
| 297. | T. Kajiyama, K. Tanaka, A. Takahara, Nano-Rheological Properties of Polymeric Solid Surfaces, 日本レオロジー学会誌, 10.1678/rheology.31.33, 31, 1, 33-40, 2003.06, [URL], Surface rheological analyses of polymeric solids were presented on the basis of scanning viscoelasticity microscopy (SVM) and lateral force microscopy (LFM). SVM observation for phase-separated polymer blend films revealed two-dimensional distribution of elasticity. In order to study surface thermal molecular motion of monodisperse polystyrene (PS), SVM and LFM measurements were made at various temperatures. Glass transition temperature, Tg, at the surface was discerned to be markedly lower than the corresponding bulk Tg, and the discrepancy of Tg between surface and bulk became larger with decreasing molecular weight. Such an intensive activation of thermal molecular motion at the PS surface can be explained in terms of an excess free volume induced by the segregated chain ends and a reduced cooperativity at the surface. Bulk Tg of miscible binary blends can be well expressed by the Gordon-Taylor equation. Extending this notion to surface, the surface composition in blends would be obtained by measuring surface Tg of each constituent as well as their blend. The surface composition in blend films of two PSs with different molecular weights was experimentally and systematically elucidated. The surface enrichment of a smaller molecular weight component became more remarkable with increasing molecular weight disparity between the two components due probably to an entropic effect.. |
| 298. | K. Tanaka, M. Tanaka, Simulation of an Aperture in the Thick Metallic Screen that Gives High Intensity and Small Spot Size Using Surface Plasmon Polariton, Journal of Microscopy, 10.1046/j.1365-2818.2003.01155.x, 210, 3, 294-300, 2003.06, The optical wave behaviour around a subwavelength aperture in a thick metallic screen is examined through three-dimensional computer simulation. Treating the metallic screen as a dielectric slab with complex-valued permittivity, it is possible to design an aperture that simultaneously provides high intensity and small spot size through the excitation of surface plasmon polaritons on the side walls of the aperture.. |
| 299. | T. Kajiyama, K. Tanaka, A. Takahara, Surface Thermal Molecular Motion of Chain end-Modified Polystyrenes, Macromolecular Symposia, 10.1002/masy.200390036, 192, 265-270, 2003.03, [URL], Surface glass transition temperature, T-g(s), of three classes of monodisperse polystyrene, proton-terminated (PS-H), alpha,omega-diamino-tertninated (alpha,omega-PS(NH2)(2)) and ap-dicarboxy-terminated (alpha,omega-PS(COOH)(2)), were studied by scanning force microscopy. T-g(s) of all samples was discernibly lower than the corresponding bulk glass transition temperature, T-g(b). Also, T-g(s) value was strongly dependent on what the chemical structure of chain end groups was. Based on the time-temperature superposition principle, apparent activation energy of the alpha(a)-relaxation process corresponding to surface segmental motion was evaluated to be approximately 230 kJ.mol(-1). This value was much smaller than the reported bulk ones, and was independent of the chemical structure of chain ends. This result implies that the cooperativity for the alpha(a)-relaxation process at the PS surface is reduced in comparison with the bulk due probably to an existence of the free space presented to polymer segments at the surface. Hence, it was concluded that the surface alpha(a)-relaxation process was activated by not only the chain end effect but also the reduced cooperativity at the surface.. |
| 300. | A. Takahara, K. Tanaka, K. Akabori, D. Kawaguchi, S. Tasaki, T. Kajiyama, Evaluation of Surface Composition of Polymer Blends Based on Lateral Force Microscopy, Abstracts of Papers of THE Amemerican Society, 225, U707-U707, 2003.03. |
| 301. | K. Tanaka, S. Dai, T. Kajiyama, K. Aoi, M. Okada, Aggregation States and Molecular Motion in Amphiphilic Poly(amido amine) Dendrimer Monolayers on Solid Substrates, Langmuir, 10.1021/la0261592, 19, 4, 1196-1202, 19 (4): 1196-1202, 2003.02. |
| 302. | D. Kawaguchi, K. Tanaka, T. Kajiyama, A. Takahara, S. Tasaki, Mobility Gradient in Surface Region of Monodisperse Polystyrene Films, Macromolecules, 10.1021/ma025667f, 36, 4, 1235-1240, 36 (4): 1235-1240, 2003.02, Surface mobility in polystyrene (PS) films was studied using (PS/deuterated PS) bilayer films, which were prepared by attaching original two surfaces together. Time evolution of the bilayer interface at various temperatures was examined by dynamic secondary ion mass spectroscopy in conjunction with neutron reflectivity. When the bilayer was annealed at a temperature above bulk glass transition temperature, T-g(b), the interfacial thickening was well expressed by the context of Fickian diffusion. On the other hand, in the case of an annealing temperature above surface glass transition temperature, T-g(s), and below T-g(b), the interface monotonically thickened with the time at first and then turned to be independent. This means that chains went across the "mobile" interface and then reached the "dead" bulk region in which the diffusivity should be frozen. Hence, it was claimed that chains could diffuse discernibly in the surface region even at a temperature lower than the T-g(b). On the basis of temperature and molecular weight dependences of quasi-equilibrium interfacial thickness after a sufficiently long time, a possible model of mobility gradient in the surface region was proposed.. |
| 303. | K. Tanaka, K. Kojio, R. Kimura, A. Takahara, T. Kajiyama, Surface Relaxation Process of Poly(methyl methacrylate) Brushes Prepared by Atom Transfer Radical Polymerization, Polym. J., 10.1295/polymj.35.44, 35, 1, 44-49, 35:44-49, 2003.01. |
| 304. | A. Takahara, D. Kawaguchi, K. Tanaka, M. Tozu, T. Hoshi, T. Kajiyama, Analysis of Surface Composition of Isotopic Polymer Blends Based on Time-of-Flight Secondary Ion Mass Spectroscopy, Appl. Surf. Sci., 10.1016/S0169-4332(02)00748-1, 203, 538-540, 203-204:538-540, 2003.01. |
| 305. | T. Kajiyama, D. Kawaguchi, K. Tanaka, Polymer Chain Diffusion at a Temperature below Its Bulk Glass Transition Temperature, Chinese J. Polym. Sci., 21, 2, 141-146, 21:141-146, 2003.01. |
| 306. | A. Sakai, K. Tanaka, T. Kajiyama, A. Takahara, Thermal Molecular Motion at Surface of Atactic Polypropylene Films, Polymer, 10.1016/S0032-3861(02)00340-3, 43, 19, 5109-5115, 2002.09, Surface molecular motion in atactic polypropylene (aPP) films was studied by scanning force microscopy. Glass transition temperature at the surface, T-g(delta), was determined to be 251 +/- 1 K on the basis of temperature dependence of lateral force, whereas its bulk glass transition temperature, T-g(b), by dynamic viscoelastic and differential scanning calorimetric measurements was 262 K. In general, polyolefin is easily oxidized, and thus, many kinds of additives are mixed in it for practical use. Hence, effects of oxidation and additives on surface properties of the aPP surface were examined as well. To achieve oxidation, the aPP films were annealed at 428 K for 100 min under the ambient atmosphere. After this treatment, T-g(delta) decreased by approximately 15 K in comparison with the intact film due to degradation of surface chains. On the contrary, in the case of the aPP containing 10 wt% antioxidant, T-g(delta) was almost the same as that of the intact film before and even after the oxidation treatment. (C) 2002 Elsevier Science Ltd. All rights reserved.. |
| 307. | K. Tanaka, T. Kajiyama, A. Takahara, S. Tasaki, A Novel Method to Examine Surface Composition in Mixtures of Chemically Identical Two Polymers with Different Molecular Weights, Macromolecules, 10.1021/ma011960o, 35, 12, 4702-4706, 35 (12): 4702-4706, 2002.06, The bulk glass transition temperature, T-g(b), of miscible binary blends can be well expressed by the Gordon-Taylor equation. Extending this notion to surface, the surface composition in the blend would be obtained by measuring the surface glass transition temperature, T-g(g), of each constituent as well as their blend. The most intriguing advantage of this technique is that labeling of a component is not necessary, unlike conventional spectroscopy. To confirm the validity of our technique, the surface composition in a mixture of polystyrene (PS) and deuterated PS (dPS) was evaluated and compared with the results by well-established surface characterization techniques, static secondary ion mass spectroscopy, and neutron reflectivity. They were in good accordance with one another within the experimental accuracy. Hence, it was claimed that the proposed method was powerful to study the surface concentration in miscible binary blends. Finally, the surface composition in blend films of two PSs with different molecular weights was experimentally and systematically elucidated. The surface enrichment of a smaller molecular weight component became more remarkable with increasing molecular weight disparity between the two components due to an entropic effect.. |
| 308. | H.-Q. Xiang, K. Tanaka, A. Takahara, T. Kajiyama, Spectroscopic and Electrochemical Characterizations of Dilithium Octacyanophthalocyanine Langmuir-Blodgett Films, Langmuir, 10.1021/la011401a, 18, 6, 2223-2228, 18:2223-2228, 2002.03. |
| 309. | K. Tanaka, H. Yu, Lipase Activity on Lipid/Polymer Binary Monolayers: Lateral Diffusion-Controlled Enzyme Kinetics, Langmuir, 18:797-804, 2002.01. |
| 310. | F. Xie, H. F. Zhang, F. K. Lee, O. K. C. Tsui, Y. Yokoe, K. Tanaka, A. Takahara, T. Kajiyama, T. He, Effect of Low Surface Energy Chain Ends on the Glass Transition Temperature of Polymer Thin Films, Macromolecules, 10.1021/ma011689a, 35, 5, 1491-1492, 35:1491-1492, 2002.01. |
| 311. | A. Sakai, K. Tanaka, T. Kajiyama, A. Takahara, Thermal Molecular Motion at Atactic Polypropylene Surfaces, Polymer, 10.1016/S0032-3861(02)00340-3, 43, 19, 5109-5115, 43:5109-5115, 2002.01. |
| 312. | H.-Q. Xiang, K. Tanaka, T. Kajiyama, Gas-Sensing Properties of Dilithium Octacyanophthalocyanine Langmuir-Blodgett Films, Langmuir, 10.1021/la026161t, 18, 23, 9102-9105, 18:9102-9105, 2002.01. |
| 313. | N. Satomi, K. Tanaka, A. Takahara, T. Kajiyama, T. Ishizone, S. Nakahama, Surface Molecular Motion of Monodisperse (alpha,omega-diamino-terminated and (alpha,omega)-Dicarboxy-Terminated Polystyrenes, Macromolecules, 10.1021/ma010126w, 34, 25, 8761-8767, 34 (25): 8761-8767, 2001.12, Surface glass transition behaviors of monodisperse alpha,omega -diamino-terminated and alpha,omega -dicarboxy-terminated polystyrenes (alpha,omega -PS(NH2)(2) and alpha,omega -PS(COOH)(2)) were studied by scanning force microscopy and were compared with the results of proton-terminated polystyrene (PS-H). All surface glass transition temperatures, T-g(s), of PS-H, alpha,omega -PS(NH2)(2), and alpha,omega -PS(COOH)(2) were discernibly lower than each corresponding bulk glass transition temperature, T-g(b). However, the magnitude of T-g(s) was strongly dependent on the chemical structure of chain end groups, because the surface concentration of chain ends varied with the surface free energy difference between the main chain part and the chain end portion, via the surface segregation or surface depletion of chain ends. This result makes it clear that chain end chemistry is one of determining factors on the magnitude of T-g(s). On the basis of the time-temperature superposition principle applied to the scanning rate dependence of lateral force as a function of temperature, the apparent activation energy, DeltaH(double dagger), of the alpha (a)-relaxation process corresponding to micro-Brownian motion at the surface was evaluated to be approximately 230 kJ mol(-1). This value is much smaller than the reported bulk ones and is independent of the chemical structure of chain ends. This result implies that the cooperativity for the alpha (a)-relaxation process at the PS surface is reduced in comparison with the bulk, probably due to the existence of the free space presented to polymer segments at the surface. Hence, it was concluded that the surface alpha (a)-relaxation process was activated by not only the chain end effect but also the reduced cooperativity at the surface. Finally, possible other factors determining on the magnitude of T-g(s) were discussed.. |
| 314. | X. Q. Jiang, K. Tanaka, A. Sakai, A. Takahara, T. Kajiyama, Surface Relaxation Behavior of Proton- and Perfluoroalkyl-Terminated Poly(2-vinylpyridine) Films, Polymer, 42, 21, 8959-8964, 2001.10, Proton- and perfluoroalkyl-terminated poly(2-vinylpyridine) (P2VP-H and P2VP-C2C8F) were anionically synthesized. Surface molecular motions of P2VP-H and P2VP-C2C8F films prepared on hydrophilic silicon wafers were examined by lateral force microscopy (LFM). Surface glass transition temperature, T-g(s), of P2VP-C2C8F was lower than that of P2VP-H probably due to the difference of the surface concentration of chain ends. Also, both T-g(s) values were lower than each corresponding bulk glass transition temperature, T-g(s). Surface molecular motion in an ultrathin film was less activated than that of the thick film, although Tin the ultrathin film remained lower than T-g(b). In the case of ultrathin films, the surface/interface area to volume ratio becomes larger, and thus the thermal molecular motion at the surface is affected by that at the polymer/substrate interface. Since molecular mobility on the substrate might be restricted owing to the polar attractive interaction between polymer segments and the hydrophilic substrate, the activation of surface molecular motion apparently turns weak for such an ultrathin film. (C) 2001 Elsevier Science Ltd. All rights reserved.. |
| 315. | D. Kawaguchi, K. Tanaka, A. Takahara, T. Kajiyama, Surface Mobile Layer of Polystyrene Film Below Bulk Glass Transition Temperature, Macromolecules, 10.1021/ma010012k, 34, 18, 6164-6166, 2001.08. |
| 316. | T. Kajiyama, R. Tominaga, K. Kojio, K. Tanaka, Structual Study of Crystal Transition from Hexagonal to Rectangular Phase of Lignoceric Acid Monolayers, Bull. Chem. Soc. Jpn., 10.1246/bcsj.74.765, 74, 4, 765-771, 74:765-771, 2001.04. |
| 317. | X. Jiang, C. Z. Yang, K. Tanaka, A. Takahara, T. Kajiyama, Effect of Chain End Group on Surface Glass Transition Temperature of Thin Polymer Film, Phys. Lett. A, 10.1016/S0375-9601(01)00150-5, 281, 5-6, 363-367, 281:363-367, 2001.01. |
| 318. | K. Kojio, K. Tanaka, A. Takahara, T. Kajiyama, Novel Method to Prepare Organosilane Monolayer on Solid Substrate, Bull. Chem. Soc. Jpn., 10.1246/bcsj.74.1397, 74, 8, 1397-1401, 74:1397-1401, 2001.01. |
| 319. | H.-Q. Xiang, K. Tanaka, A. Takahara, T. Kajiyama, Reversible Reduction and Reoxidation of Langmuir-Blodgett Films of Octacyanophthalocyanine Dilithium Complex, Chem. Lett., 10.1246/cl.2001.536, 6, 536-537, 536-537, 2001.01. |
| 320. | N. Satomi, K. Tanaka, A. Takahara, T. Kajiyama, Effect of Internal Bulk Phase on Surface Viscoelastic Properties by Scanning Probe Microscopy, Macromolecules, 10.1021/ma001831s, 34, 18, 6420-6423, 34:6420-6423, 2001.01. |
| 321. | A. Takahara, K. Nakamura, K. Tanaka, T. Kajiyama, Polymer battery R&D in the U.S., Macromolecular Symposia, 10.1002/1521-3900(200010)159:13.0.CO;2-O, 159, 229-245, 2000.12, [URL], Polymer electrolytes that have been developed for battery applications fall into two general classes, neat or "pure" polymer and plasticized or gel in which the polymer is combined with a conducting organic electrolyte. The polyethylene oxide (PEO) and its modifications are typical of the "pure" polymer electrolytes. They have poor conductivity at room temperatures, but at elevated temperatures, their conductivity is of the order of 10 -3 to 10 -4 S/cm. The PEO electrolytes have found application in the high temperature (>60°C) lithium metal anode battery systems. The high temperature necessary for good operation makes them unsuitable for use in small consumer appliances. The polymer electrolyte battery development activities have resulted in several high performance battery systems now just entering the market. Not all of the developments have resulted in commercial cell production. The commercialization activities of high performance lithium-ion (Li-Ion) batteries have been based on two general plastic polymer systems: poly-vinylidene difluoride-hexafluoropropylene copolymer (PVdF-HFP) and polyacrylates. The polymer cells are expected to have advantages in manufacturing, flexibility, thin cell formats and lightweight packaging. Important parameters in PVdF gel electrolyte performance include the electrolyte type (combination of organic carbonates), temperature, and HFP copolymer content. Li-Ion coin cells fabricated with a polyolefin separator with either liquid electrolyte or with the PVdF gel polymer electrolyte have equivalent performance.. |
| 322. | T. Kajiyama, D. Kawaguchi, N. Satomi, K. Tanaka, A. Takahara, Surface Glass Transition Behaviors of Glassy Polymers, Reports on Progress in Polymer Physics in Japan, 43, 311-330, 2000.12, Recent studies of thermal molecular motions at polymer surfaces are reviewed. Although many arguments have been still going on, many results support a consistent notion that surface molecular motion is much more vigorous than that in its interior bulk region. Finally, surface dynamics at temperature below its bulk glass transition is also reviewed.. |
| 323. | K. Tanaka, A. Takahara, T. Kajiyama, Rheological Analysis of Surface Relaxation Process of Monodisperse Polystyrene Films, Macromolecules, 10.1021/ma000406w, 33, 20, 7588-7593, 33 (20): 7588-7593, 2000.10, Surface glass transition temperature, Tg s, of monodisperse polystyrene (PS) films was determined from the temperature dependence of lateral force at a given scanning rate. The end groups of the PS were composed of sec-butyl group and a repeating unit terminated by proton. Tg s of the PS films was discerned to be markedly lower than its bulk Tg, Tg b, in the entire number-average molecular weight, Mn, range, 4.9 K to 1460 K. The Mn dependence of Tg s was analyzed on the basis of a simple power law. The exponent of Mn related to Tg s was -0.60±0.03 in contrast to the power of -0.5 from the Mayes scaling argument that is based on both chain ends being perfectly localized at the surface. This result implies that the surface localization of end groups of the PS used here is not complete. The Tg s extrapolated to the infinite Mn was found to be lower than the corresponding Tg b by approximately 20 K. The apparent activation energy of the surface αa-relaxation process for the PS obtained from Arrhenius plot was 230±10 kJ·mol-1, significantly smaller than that for the bulk PS. Also, it was shown on the basis of Ngai's coupling model that the cooperative motion at the surface can be achieved much easier than its internal bulk phase. Thus, the difference between the Tg s and the Tg b for the infinite Mn PS was explained in terms of the size and/or energy barrier reduction of the cooperative movement for the surface αa-relaxation process, which might be arisen from the existence of the free space presented to polymer segments at the surface.. |
| 324. | T. Kajiyama, N. Satomi, Y. Yokoe, D. Kawaguchi, K. Tanaka, A. Takahara, Effect of End Group Chemistry on Surface Molecular Motion of Monodisperse Polystyrene Films, Macromol Symp, 10.1002/1521-3900(200010)159:13.0.CO;2-R, 159, 35-42, 2000.10. |
| 325. | A. Takahara, K. Nakamura, K. Tanaka, T. Kajiyama, Surface Aggregation Structure and Surface Mechanical Properties of Binary Polymer Blend Thin Films., Macromol Symp, 10.1002/1521-3900(200010)159:13.0.CO;2-U, 159, 89-96, 2000.10. |
| 326. | K. Tanaka, H. Yu, Polymer Modulated, Diffusion-Controlled Enzyme Kinetics on Monolayers, Quaternary International, 41, 2, 1809-1810, 2000.08, A study was carried out to examine the monolayer dynamics and the hydrolysis kinetics of umbelliferone stearate (UMB-C18) on binary monolayers composed of dilauroylphosphatidylcholine (DLPC) and another viscosifier, PtBMA. Results of this study were compared to previous results using a different viscosifier, cholesterol, of the lipid monolayer.. |
| 327. | T. Kajiyama, K. Tanaka, N. Satomi, A. Takahara, Surface Rheology of Polymeric Solids, Chinese Journal of Polymer Science, 18, 3, 239-248, 2000.05, Surface molecular motions of amorphous polymeric solids have been directly measured on the basis of scanning viscoelasticity microscopic (SVM) and lateral force microscopic (LFM) measurements. SVM and LFM measurements were carried out fur films of conventional monodisperse polystyrene (PS) with sec-butyl] and proton-terminated end groups at room temperature, In the case of the number-average molecular weight, M-n, less than ca. 4.0 x 10(4), the surface was in a glass-rubber transition state even though the bulk glass transition temperature, T-g was far above room temperature, meaning that the surface molecular motion was fairly active compared with that in the bulk. LFM measurements of the monodisperse PS films at various scanning rates and temperatures revealed that the time-temperature superposition was applicable to the surface mechanical relaxation behavior and also that the surface glass transition temperature, T-g(sigma) was depressed in comparison with the bulk one even though the magnitude of M-n was fairly high at 1.40 x 10(5). The surface molecular motion of monodisperse PS with various chain end groups was investigated on the basis of temperature-dependent scanning viscoelasticity microscopy (TDSVM). The T(g)(sigma)s for the PS films with M-n of 4.9 x 10(3) to 1.45 x 10(6) measured by TDSVM were smaller than those for the bulk one, with corresponding M(n)s, and the T(g)(sigma)s for M(n)s smaller than ca. 4.0 x 104 were lower than room temperature (293 K), The active thermal molecular motion at the polymeric solid surface can be interpreted in terms of an excess free volume near the surface region induced by the surface localization of chain end groups. In the case of M-n = ca. 5.0 x 10(4), the T(g)(sigma)s for the alpha,omega-diamino-terminated PS (alpha,omega-PS(NH2)(2)) and alpha,omega-dicarboxy-terminated PS (alpha,omega-PS(COOH)(2)) films were higher than that of the PS film. The change of T(g)(sigma)s for the PS film with various chain end groups can be explained in terms of the depth distribution of chain end groups at the surface region depending on the relative hydrophobicity.. |
| 328. | K. Tanaka, S. P. Mecca, H. Yu, Lipase Catalysis on Monolayers at the Air/Water Interface. 2. Diffusion-Controlled Kinetics on Quasi-Two-Dimension, Langmuir, 10.1021/la990925w, 16, 6, 2672-2676, 2000.03, [URL], Homogeneous exoplasmic leaflets of biomembrane are mimicked by lipid monolayers at the air/water interface. The reaction rates of lipase (Pseudomonas cepacia) catalyzed hydrolysis of a substrate (umbelliferone stearate) on L-α-dilauroylphosphatidylcholine/cholesterol mixed monolayers at the air/water interface are examined as a function of cholesterol composition, which is to vary the dynamics of the system. Lateral mobility as a measure of dynamics of phospholipids and adsorbed lipase molecules are probed with the technique of fluorescence recovery after photobleaching. Upon correlating the lateral diffusion coefficients of a probe lipid and lipase with the interfacial hydrolysis kinetics, we show for the first time that the catalytic reactions on the monolayers are diffusion-controlled. Moreover, our results are in a quantitative agreement with the two-dimensional reaction dynamics theory of Torney and McConnell.. |
| 329. | T. Kajiyama, K. Tanaka, N. Satomi, A. Takahara, Surface Glass Transition Temperatures of Monodisperse Polystyrene Films by Scanning Force Microscopy, Science and Technology of Advanced Materials, 10.1016/S1468-6996(99)00005-4, 1, 1, 31-35, 2000.03, [URL], Surface molecular motion of monodisperse polystyrene (PS) films was examined by scanning viscoelasticity microscopy (SVM) in conjunction with lateral force microscopy (LFM). The dynamic storage modulus, E1, and loss tangent, tan δ, at a PS film surface with a smaller number-average molecular weight, Mn, than 40k were found to be smaller and larger than those for the bulk sample even at room temperature, meaning that the PS surface is in a glass-rubber transition state or a fully rubbery one at this temperature if the Mn, is small. In order to elucidate quantitatively how vigorous the molecular motion at the PS surface is, SVM and LFM measurements were made at various temperatures. The glass transition temperature, Tg, at the surface was discerned to be markedly lower than its bulk Tg, and the discrepancy of Tg between surface and bulk becomes larger with the decreasing Mn. Such an intensive activation of thermal molecular motion at the PS surfaces can be explained in terms of an excess free volume in the vicinity of the film surface induced by the preferential segregation of chain end groups. © 2000 Elsevier Science Ltd. All rights reserved.. |
| 330. | K. Tanaka, P. A. Manning, H. Yu, Lipase Catalysis on Monolayers at the Air/Water Interface. 1.Kinetic Rate Constants on Quasi-Two-Dimension, Langmuir, 16:2665-2671, 2000.01. |
| 331. | N. Miki, K. Tanaka, A. Takahara, T. Kajiyama, Secondary Ion Mass Spectroscopic Analysis of Copper Migration at the Copper/Polyimide Interface, J.Vac.Sci.Technol.B, 10.1116/1.591191, 18, 1, 313-316, 18:313-316, 2000.01. |
| 332. | T. Kajiyama, D. Kawaguchi, A. Sakai, N. Satomi, K. Tanaka, A. Takahara, Determination Factors on Surface Glass Transition Temperatures of Polymeric Solids, High Perform. Polym., 10.1088/0954-0083/12/4/314, 12, 4, 587-597, 12:587-597, 2000.01. |
| 333. | X. Jiang, K. Tanaka, A. Takahara, S. Nakahama, T. Kajiyama, Chain end Group-Induced Surface Ordering in Poly(styrene-b-4-vinylpyridine) Symmetric Diblock Copolymer Films, Polymer. J., 31, 11 pt 2, 1015-1020, 1999.12, The proton-terminated and fluoroalkyl-terminated poly(styrene-b-4-vinylpyridine) [P(St-b-4VP)] symmetric diblock copolymers were synthesized by a sequential anionic polymerization. The surface chemical composition, surface morphology and surface mechanical properties of the diblock copolymer thin films were investigated on the basis of the angular-dependent X-ray photoelectron spectroscopic (ADXPS) measurement and transmission electron microscopic (TEM) observations. The XPS results revealed that in the case of the proton-terminated P(St-b-4VP) film, the surface weight fraction of poly(4-vinyl pyridine)(P4VP) decreased dramatically after annealing above the glass transition temperature, Tg of P(St-b-4VP), resulting in the formation of polystyrene (PS) surface layer in order to minimize the interfacial free energy at air-polymer interface. Whereas, in the cases of the fluoroalkyl-terminated P(St-b-4VP) films [P(St-b-4VP)-C 2 C F X where -C 2 C F X shows fluoroalkyl end group], the surface weight fraction of P4VP decreased slightly and still was more than 30% even after the annealing treatment. TEM observation revealed that the lamellar structure was formed in all P(St-b-4VP). The surface order and orientation of lamellar structure were strongly influenced by the chain end group species. That is, in the case of the proton-terminated P(St-b-4VP) film, the lamellar structure was oriented parallel to the film surface and the outermost layer was composed of PS. On the other hand, in the case of P(St-b-4VP)-C 2 C F X , the well-developed lamellae was tilted ca. 45 deg to the film surface and the alternating PS and P4VP layers were exposed to the air interface. These results indicate that the surface order and orientation of microphase-separated lamellar structure strongly depend on the chemical structure of the chain end group.. |
| 334. | T. Kajiyama, N. Satomi, K. Tanaka, A. Takahara, Surface, Thermal and Mechanical Characteristics of Polymeric Solids, Macromolecular Symposia, 143, 171-183, 1999.08, [URL], Surface molecular motions of amorphous polymeric solids have been directly measured on the basis of lateral force microscopic (LFM) and scanning viscoelasticity microscopic (SVM) measurements. SVM measurement revealed that the molecular motion at the surface of the monodisperse polystyrene (PS) film with Mn less than ca.30 k was fairly activated compared with that in a bulk region, mainly due to the surface segregation of chain end groups. Tempereature dependent LFM and SVM measurement revealed that the surface glass transition temperature, Tg of the monodisperse PS film was lower than the bulk one, even though Mn was fairly large as 140 k and also, that the time-temperature superposition was applicable to the surface relaxation process. The chain end group segregation at the air/PS interface was verified from the dynamic secondary ion mass spectroscopic (DSIMS) depth profiling of the proton and deuterium ion for the end-labeled deutrated-PS (dPS) film. These results suggest that the surface Tg is depressed due to an increase in free volume near surface region, being induced by the preferential surface localization of chain end groups.. |
| 335. | K. Tanaka, P. A. Manning, V. K. Lau, H. Yu, Lipid Lateral Diffusion in Dilauroylphosphatidylcholine/Cholesterol Mixed Monolayers at the Air/Water Interface, Langmuir, 15 (2): 600-606, 1999.01. |
| 336. | A. Takahara, X. Jiang, N. Satomi, K. Tanaka, T. Kajiyama, Analysis of Surface Mechanical Properties of Polymer Blend Ultrathin Films by Scanning Force Microscopy, Key Engineering Materials, 137, 79-86, 1998.12, Scanning viscoelasticity microscopy (SVM) is used in studies of the surface mechanical properties of polymeric solids. It was revealed that the surface molecular motion is fairly different from bulk one due to the surface segregation of chain end groups. The two-dimensional mapping of the surface mechanical properties for the polymer blend ultrathin films was carried out on nanometer scale.. |
| 337. | T. Kajiyama, K. Tanaka, A. Takahara, Study of the Surface Glass Transition Behaviour of Amorphous Polymer Film by Scanning-Force Microscopy and Surface Spectroscopy, Polymer, 10.1016/S0032-3861(98)00049-4, 39, 19, 4665-4673, 1998.09, The surface molecular motion of amorphous polymeric solids has been directly measured by lateral force microscopic (LFM), scanning viscoelasticity microscopic (SVM) and differential X-ray photoelectron spectroscopic (D-XPS) measurements. SVM and LFM measurements revealed that the molecular motion on the surface of the monodisperse PS film with Mn less than ca. 30 k was fairly active compared with that in the bulk, mainly due to the surface segregation of chain end groups. The chain end group segregation at the air/PS interface was verified by dynamic secondary ion mass spectroscopic depth profiling of the proton and deuterium ion for end-labelled PS film. These results suggest that surface T-g is depressed because of an increase in free volume near the surface region, induced by the preferential surface localization of chain end groups. D-XPS was utilized for the characterization of surface molecular motion of symmetric poly(styrene-block-methyl methacrylate) diblock copolymer [P(St-b-MMA)] films. It was confirmed by D-XPS that the surface molecular motion of the PS component in [P(St-b-MMA)] diblock copolymer films was gradually activated with decreasing depth from the air/polymer interface. (C) 1998 Elsevier Science Ltd. All rights reserved.. |
| 338. | K. Tanaka, A. Takahara, T. Kajiyama, Surface Molecular Aggregation Structure and Surface Molecular Motions of High-Molecular-Weight Polystyrene Low-Molecular-Weight Poly(methyl methacrylate) Blend Films, Macromolecules, 10.1021/ma9709866, 31, 3, 863-869, 31 (3): 863-869, 1998.02, Surface molecular aggregation structure and surface molecular motions of high-molecular-weight polystyrene/low-molecular-weight poly(methyl methacrylate) (HMW-PS/LMW-PMMA) blend films were investigated on the basis of X-ray photoelectron spectroscopic measurements and scanning force microscopic observations. Monodisperse PS with M-n = 1450k, where M-n denotes the number-average molecular-weight, and monodisperse PMMAs with M-n 1.2k, 4.2k, 40.5k, 144k, and 387k were used as HMW-PS and LMW-PMMAs, respectively. Static contact angle measurements revealed that the magnitudes of surface free energy, gamma, of PMMAs for all M(n)s studied here were higher than that of PS with M-n = 1450K. In the case of the (HMW-PS/LMW-PMMA) blend films, in which the M-n for each PMMA was less than 144K, PMMA was preferentially segregated at the air-polymer interface, even though PMMA had a main chain with a higher gamma compared with that of PS. It was found from scanning viscoelasticity microscopic measurements that the surface molecular motion of the (PS with M-n = 1450k/PMMA with M-n = 4.2k) blend film was fairly activated in comparison with that of the bulk one due to the surface segregation of LMW-PMMA. The surface enrichment of LMW-PMMA can be explained by enthalpic and entropic terms as follows. (1) Since the magnitudes of gamma of both chair! end groups of a polymer chain synthesized by an ordinary living anionic polymerization are smaller than that of the main chain part, the chain end groups are preferentially segregated at the surface. Therefore, the chain end effect at the air-polymer interface becomes more remarkable with a decrease of M,, due to an increases in the number density of chain end groups. (2) Since polymeric chains existing in a surface region are compressed along the direction perpendicular to the film surface, the surface chains take smaller conformational entropy in a confined state compared with that of bulk chains. The difference in conformational entropy between the surface chain and the bulk one, that is, the conformational entropic penalty of the polymeric chain at the surface, decreases nith a decrease in M-n. Then, when the enthalpic and entropic effects mentioned above overcome the gamma difference of main chain parts between PS and PMMA, PMMA with higher gamma is stably enriched at the blend film surface.. |
| 339. | X. Jiang, K. Tanaka, A. Takahara, T. Kajiyama, Effect of Chain End Group Hydrophobicity on Surface Aggregation Structure of Poly(stylene-block-4-vinylpyridine) Symmetric Diblock Copolymer Films, Polymer, 10.1016/S0032-3861(97)00567-3, 39, 12, 2615-2620, 39 :2615-2620, 1998.01. |
| 340. | T. Kajiyama, K. Tanaka, A. Takahara, Surface Segregation of the Higher Surface Free Energy Component in Symmetric Polymer Blend Films, Macromolecules, 10.1021/ma971247s, 31, 11, 3746-3749, 31 :3746-3749, 1998.01. |
| 341. | K. Tanaka, X. Jiang, K. Nakamura, A. Takahara, T. Kajiyama, T. Ishizone, A. Hirao, S. Nakahama, Effect of Chain End Chemistry on Surface Molecular Motion of Polystyrene Films, Macromolecules, 10.1021/ma9712561, 31, 15, 5148-5149, 31 :5148-5149, 1998.01. |
| 342. | T. Kajiyama, K. Tanaka, N. Satomi, A. Takahara, Surface Relaxation Process of Monodisperse Polystyrene Film Based on Lateral Force Microscopic Measurements, Macromolecules, 10.1021/ma971274i, 31, 15, 5150-5151, 31 :5150-5151, 1998.01. |
| 343. | W. K. Lee, J. S. Yoon, K. Tanaka, N. Satomi, X.-Q. Jiang, A. Takahara, C. S. Ha, T. Kajiyama, Relationships Between Lateral Force and Viscoelastic Properties for Amorphous Polymer Films Based on Lateral Force Microscopy, Polymer Bulletin, 10.1007/s002890050161, 39, 3, 369-376, 1997.09, [URL], The relationships between lateral force and viscoelastic properties of amorphous polymer surfaces with Tg's lower and higher than room temperature (295 K, RT) and their blend systems have been studied on the basis of lateral force microscopic (LFM) measurement. Under the conditions of scanning rate of 10(2) - 10(5) nm sec(-1), normal load of 5 nN and RT, the lateral forces of poly(methyl methacrylate) (PMMA) and polyisoprene (PI) homopolymers with Tg's fairly higher and lower than RT, respectively, did not depend on the scanning rate. Whereas, the lateral force of poly(methyl acrylate) (PMA) with Tg less than or equal to RT decreased with an increase in the scanning rate. Also, poly(vinyl acetate) (PVAc) with Tg greater than or equal to RT showed slight dependence on the scanning rate. The scanning rate dependence of lateral force was similar to the frequency dependence of mechanical loss modulus. The results indicate that the magnitude of lateral force strongly depends on the state of thermal molecular motion. The lateral force-viscoelastic properties of miscible polymer blends was also investigated by LFM.. |
| 344. | W. K. Lee, K. Tanaka, A. Takahara, T. Kajiyama, C. S. Ha, Surface Structure of Blend Films of Styrene/acrylonitrile Copolymer and Poly(methyl methacrylate)(PMMA) or Hydrolyzed PMMA, Bulletin of THE Korean Chemical Society, 18, 9, 958-961, 1997.09, The compatibility and the surface structure of blends of poly(styrene-co-acrylonitrile) (SAN) with either poly (methyl methacrylate) (PMMA) or hydrolyzed PMMA (H-PMMA) were studied in terms of film thickness, interaction, and surface free energy difference on the basis of X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform IR spectroscopy and atomic force microscopy. The. XPS measurement showed that the surface enrichment of (PMMA/SAN) blends with different AN contents of SAN and with different carboxyl acid contents of PMMA was dependent on the molecular interaction, the surface free energy difference between components and the sample preparation history. It was found that the compatibility of H-PMMA and SAN was reduced with increasing carboxyl acid content of PMMA.. |
| 345. | T. Kajiyama, K. Tanaka, A. Takahara, Surface Thermomechanical and Glass Transition Temperature Measurements of Polymeric Solids, Macromolecular Symposia, 118, 677-682, 1997.06, [URL], The surface molecular motion of polymeric solids was investigated on the basis of scanning force microscopic and temperature-dependent X-ray photoelectron spectroscopic measurements. The surface of the monodisperse polystyrene films was in a glass-rubber transition state even at 293 K in the case of number-average molecular weight less than ca. 30k. The surface glass transition temperature, Tgs for the symmetric poly(styrene-block-methyl methacrylate) diblock copolymer films were much lower than those for the bulk samples. A remarkable depression of Tg at the air-polymer interface was explained by the surface localization of chain end groups.. |
| 346. | T. Kajiyama, K. Tanaka, A. Takahara, Surface Molecular Motion of the Monodisperse Polystyrene Films, Macromolecules, 10.1021/ma960582y, 30, 2, 280-285, 30 :280-285, 1997.01. |
| 347. | K. Tanaka, A. Takahara, T. Kajiyama, Effect of Polydispersity on Surface Molecular Motion of Polystyrene Films, Macromolecules, 10.1021/ma970057e, 30, 21, 6626-6632, 30 :6626-6632, 1997.01. |
| 348. | T. Kajiyama, K. Tanaka, A. Takahara, Surface Molecular Motion of Amorphous Polymeric Solids, Bull. Chem. Soc. Jpn., 10.1246/bcsj.70.1491, 70, 7, 1491-1503, 70 :1491-1503, 1997.01. |
| 349. | T. Kajiyama, K. Tanaka, A. Takahara, Analysis of Surface Molecular Motion of Amorphous Polymeric Solids on the Basis of Scanning Force Microscopy and X-ray Photoelectron Spectrocopy, Peoc. Japan Acad. B, 73 :132-137, 1997.01. |
| 350. | A. Takahara, K. Tanaka, S. R. Ge, T. Kajiyama, Scanning Force Microscopic Study of Morphology and Properties of Multiphase Polymer Surface, Polym Prepr, 37, 2, 589-590, 1996.08. |
| 351. | K. Tanaka, A. Taura, S.-R. Ge, A. Takahara, T. Kajiyama, Molecular Weight Dependence of Surface Dymamic Viscoelastic Properties for the Monodisperse Polystyrene Film, Macromolecules, 10.1021/ma951378y, 29, 8, 3040-3042, 29 :3040-3042, 1996.01. |
| 352. | K. Tanaka, A. Takahara, T. Kajiyama, Film Thickness Dependence of Surface Structure of Immiscible Polystyrene/Poly(methyl methacrylate) Blends, Macromolecules, 10.1021/ma951140+, 29, 9, 3232-3239, 29 :3232-3239, 1996.01. |
| 353. | 田中敬二、高原淳、梶山千里, 高分子固体膜表面の分子運動特性, 高分子論文集, 53 :582-591, 1996.01. |
| 354. | T. Kajiyama, K. Tanaka, S.-R. Ge, A. Takahara, Morphology and Mechanical Properties of Polymer Surfaces Via Scanning Force Microscopy, Progress in Surface Science, 10.1016/0079-6816(96)00006-8, 52, 1, 1-52, 1996.01, [URL], Scanning force microscopy is used in studies of the surface morphology and surface mechanical properties of polymeric solids. Several examples are presented to illustrate that SFM is a powerful and promising tool for investigations, such as, polyethylene single crystal, polymer blend thin films and polymerized organosilane monolayers. The imaging of nano-mechanical properties, such as, lateral force and elastic modulus of phase-separated polymer surfaces by SFM is presented. The application of SFM to the quantitative evaluation of surface viscoelasticity is also summarized.. |
| 355. | K. Tanaka, A. Takahara, T. Kajiyama, Surface Molecular Motion of Polymeric Solid Films, 高分子論文集, 10.1295/koron.53.582, 53, 10, 582-591, 1996.01, [URL], Surface dynamic storage modulus, E′, and surface loss tangent, tan δ, of monodisperse polystyrene (PS) films with various molecular weights were evaluated at 293 K on the basis of scanning viscoelasticity microscope (SVM) which was designed by the authors. In the case of the PS film with a number-average molecular weight, Mn, lower than ca. 30 k, the magnitudes of surface E′ and surface tan δ were smaller and larger than the magnitudes showing a glassy state, respectively. Thus, it seems reasonable to conclude that the PS film surface with Mn less than ca. 30 k is in a glass-rubber transition state even at 293 K. The scanning rate dependence of lateral force for the monodisperse PS films was investigated at 293 K by lateral force microscopy (LFM). Since the magnitude of lateral force was apparently dependent on the scanning rate, especially in the case of Mn lower than ca. 40 k, it seems reasonable to conclude that the PS film surface with Mn less than ca. 40 k is in a glass-rubber transition state at 293 K. The LFM results agreed well with the SVM results if the scanning rate of cantilever tip for LFM measurements corresponded to the measuring frequency for SVM measurements. The depth dependence of surface glass transition temperature, Tg, of the poly-(styrene-block-methyl methacrylate) diblock copolymer film was also investigated on the basis of the combination of temperature-dependent and angular-dependent X-ray photoelectron spectroscopic (TDXPS and ADXPS) measurements. It was revealed that Tg at the film surface was much lower than that of the bulk sample and its magnitude increased with the depth from the free surface. The remarkable depression of Tg at the polymeric surface was explained by the excess free volume induced due to the surface localization of chain end groups. The surface enrichment of chain end groups was confirmed by dynamic secondary ion mass spectroscopic measurement.. |
| 356. | K. Tanaka, J.-S. Yoon, A. Takahara, T. Kajiyama, Ultrathinning-Induced Surface Phase Separation of Polystyrene/Poly(vinyl methyl ether) Blend Film, Macromolecules, 10.1021/ma00108a021, 28, 4, 934-938, 28 : 934-938, 1995.01. |
| 357. | T. Kajiyama, K. Tanaka, A. Takahara, Depth Dependence of the Surface Glass Transition Temperature of a Poly(styrene-block-methyl methacrylate) Diblock Copolymer Film on the Basis of Temperature-Dependent X-ray Photoelectron Spectroscopy, Macromolecules, 10.1021/ma00113a059, 28, 9, 3482-3484, 28 : 3482-3484, 1995.01. |
| 358. | K. Tanaka, A. Takahara, T. Kajiyama, Surface Molecular Motion in Thin Films of Poly(styrene-block-methyl methacrylate) Diblock Copolymer, Acta Polym., 10.1002/actp.1995.010460612, 46, 6, 476-482, 46 : 476-482, 1995.01. |
| 359. | T. Kajiyama, K. Tanaka, I. Ohki, S.-R. Ge, A. Takahara, Direct Observation of Surface Morphology and Surface Viscoelastic Properties of Polymeric Solids Based on Scanning Force Microscopy, Proc.Japan Acad. B, 10.2183/pjab.71.75, 71, 2, 75-80, 71 :75-80, 1995.01. |
| 360. | T. Kajiyama, K. Tanaka, I. Ohki, S.-R. Ge, J.-S. Yoon, A. Takahara, Imaging of Dynamic Viscoelastic Properties of a Phase-Separated Polymer Surface by Forced Oscillation Atomic Force Microscopy, Macromolecules, 10.1021/ma00104a061, 27, 26, 7932-7934, 27 :7932-7934, 1994.01. |
| 361. | M. Tanaka, K. Tanaka, On a New Boundary Element Solution Scheme for Elastoplasticity, Ingenieur-Archiv, 10.1007/BF00778424, 50, 5, 289-295, 1981.09, A new boundary element discretization scheme is proposed for three-dimensional elastoplasticity. The governing equation of the problem is transformed into a set of integral equations in the domain and on the boundary. The resulting integral equations are discretized by means of boundary elements as well as volume elements. The system of linear equations thus obtained is solved simultaneously. The formulation is made in terms of increments and also Green's functions available in the literature for elastostatics. Since the domain is also discretized into volume elements in the proposed solution scheme, the incremental solutions at every loading step can be obtained without any iterative procedure. © 1981 Springer-Verlag.. |
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