Language：Others   Publishing type：Research paper (scientific journal)  

Single carbon fiber (CF)-embedded thermoset epoxy resin (EP) and thermoplastic polycarbonate (PC) specimens were prepared to clarify the interfacial interaction between CF and a matrix polymer and the deformation behavior of the carbon fiber and a matrix polymer. Stress-strain curves of EP and PC samples including and excluding CFs showed yields at approximately 70 MPa. In situ polarized high-speed camera images of the samples revealed the effect of CF on stress propagation. Moreover, the retardation of the fiber/polymer interface was large and that of PC was higher than that of EP. Microbeam small/wide-angle X-ray scattering measurements revealed that the orientation of the polymer chains near the CF and the turbostratic structure of the CFs occurred for both EP and PC; craze formation was suppressed because of CF during the deformation process for PC.

DOI： 10.1021/acsapm.3c01959

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.jpclett.3c02376

Language：Others   Publishing type：Research paper (scientific journal)  

Although carbon-fiber-reinforced polymers (CFRPs) have excellent mechanical properties and are considered sustainable, an improved understanding of the fatigue behavior of these materials is crucial for expanding their application scope. The aim of this study is to clarify the fatigue mechanism of CFRPs using in situ and offline mapping by small-angle/wide-angle X-ray scattering (SAXS/WAXS) measurements. The resulting findings provide information about the interface between the carbon fibers (CFs) and epoxy matrix, as well as changes in epoxy chain structure and internal structure of the CFs. For example, the in situ SAXS profiles revealed an increase in intensity with cycling, which may be related to void and crack formation. Furthermore, the in situ WAXS profiles indicated that the 0° fibers became less ordered and that some destruction of the turbostratic structure occurred. Offline SAXS/WAXS mapping after fatigue tests with low and high loads revealed information about changes in the epoxy resin and carbon fibers, respectively, as well as the shapes of cracks. In particular, offline mapping confirmed that epoxy chain relaxation occurred rapidly after failure.

DOI： 10.1177/00219983231204407

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Single-lap joint (SLJ) specimens were prepared using two stainless steel substrates as adherends and polyurethanes (PU) as an adhesive and then employed for adhesion testing. To investigate the internal structure of the PU adhesive during the shear deformation process, the in situ synchrotron radiation microbeam small-angle and wide-angle X-ray scattering (SAXS and WAXS) measurements were carried out. A lab-made portable tensile tester was developed for the SAXS/WAXS measurement during lap shear deformation. The structure of adhesive bulk was also investigated during the simple uniaxial deformation for the comparison. An isotropic scattering ring-which was formed from the periodic structure of hard segment domains of the PU adhesive-was clearly observed in the SAXS pattern at the initial state. This isotropic ring changed to an ellipsoid shape whose minor and major axes were tilted from the stretching direction. The spacing of the hard segment domains of PU adhesives increased, and the tilt angle of the stress direction was merged with the stretching direction with an increase in the applied deformation. The orientation direction of the hard segment domains and molecular chain of the soft segment changed with a similar trend. Furthermore, the degree of change in these values was larger at the edge of the adhesive of the SLJ specimens, indicating the existence of spatial distribution of direction and the value of stress in the adhesive during lap shear deformation. These findings are expected to be quite useful for practical design of adhesives.

DOI： 10.1021/acsapm.2c00436

Repository Public URL： https://hdl.handle.net/2324/7172245

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.langmuir.1c01762

Language：Others   Publishing type：Research paper (scientific journal)  

Crystalline behavior of poly(L-lactic acid) (PLLA), polybutylene succinate (PBS) and their (PLLA/PBS) blends were investigated using differential scanning calorimetry, dynamic viscoelastic property, in situ simultaneous small-angle X-day scattering (SAXS)/wide-angle X-ray diffraction (WAXD) measurements, and scanning electron microscopic observation. The films of PLLA, PBS and (PLLA/PBS) blends with the various weight ratios were prepared by quenching from the molten phase, and then, various measurements were conducted during the crystallization process. Dynamic viscoelastic measurement revealed that the temperature, at which the crystallization of PLLA occurs, shifted to lower temperature side with an increase in the PBS ratio. Furthermore, in situ SAXS/WAXD measurements revealed that the crystallization rate of PLLA increased with blending PBS and crystallization of PBS was almost restricted by blending PLLA although homo PBS was partially crystallized even by quenching from the molten phase due to quite rapid crystallization rate of PBS. These phenomena are due mainly to the molecular dispersed state of PLLA and PBS components formed in the molten state. The results obtained in this study are quite useful to control mechanical properties as well as the crystalline state including crystallinity and melting temperature, and crystal lattice, for PLLA/PBS blend.

DOI： 10.1007/s10965-022-02986-8

Language：Others   Publishing type：Research paper (scientific journal)  

Isotactic polypropylene (iPP) is one of the most commonly used polymers owing to its excellent mechanical properties and well-balanced physical properties. These properties can be achieved and controlled through a better understanding of its hierarchical structures. The crystal structures of iPP thin films of ∼120 nm thickness formed on graphite and silicon substrates were investigated via grazing incidence wide-angle X-ray diffraction (GIWAXD) with hard and tender X-rays along with grazing incidence small-angle X-ray scattering, atomic force microscopy, and transmission electron microscopy. The lamellae were found to be edge-on-oriented on the graphite substrate due to epitaxial iPP crystal growth and flat-on-oriented on the silicon substrate due to iPP crystal growth along the thermodynamically dominant orientation. GIWAXD results obtained with tender X-rays revealed that the orientation of the crystal lamellae did not change along the thickness direction and that the degree of crystallinity at the surface was lower than that in the interior of the iPP thin films for each substrate. These results indicate that crystallization at the substrate-film interface played a significant role in the formation of the crystal structure of the iPP thin film, that is, the crystals grew throughout the thin films along the substrate-induced orientation even in the case of edge-on orientation, where the growth axes of the crosshatched lamellae were not parallel to the thickness direction. The relationship between the growth axes of lamella and the growth of surface-induced orientation along the normal direction of the substrates was successfully clarified for the first time using the thin film systems. The obtained results can be extended to interface-induced crystallization inside bulk composite materials.

DOI： 10.1016/j.polymer.2022.124665

Language：Others   Publishing type：Research paper (scientific journal)  

Transformable double hydrophilic block copolymer assemblies are valid as a biocompatible smart macromolecular system. The molecular mechanisms in the spontaneous assembly of double zwitterionic diblock copolymers composed of a poly(carboxybetaine methacrylate) (PCB2) and a poly(sulfobetaine methacrylate) (PSB4) chains (PCB2-b-PSB4) were investigated by the modulation of the aggregates in response to nondetergent zwitterions. The PCB2-b-PSB4 diblock copolymers with a high degree of polymerization PSB4 block produced aggregates in salt-free water through “zwitterion-specific” interactions. The PCB2-b-PSB4 aggregates were dissociated by the addition of nondetergent sulfobetaine (SB4) and carboxybetaine (CB2) molecules, while the aggregates showed different aggregation modulation processes for SB4 and CB2. Zwitterions with different charged groups from SB4 and CB2, glycine and taurine, hardly disrupted the PCB2-b-PSB4 aggregates. The PCB2-b-PSB4 aggregate modulation efficiency of SBs associated with the intercharge hydrocarbon spacer length (CSL) rather than the symmetry with the SB in the PSB chain. These zwitterion-specific modulation behaviors were rationalized based on the nature of zwitterions including partial charge density, dipole moment, and hydrophobic interactions depending on the charged groups and CSL.

DOI： 10.1021/acs.langmuir.1c02809

Language：English   Publishing type：Research paper (scientific journal)  

The construction of a deep learning model and visualization of judgment regions were conducted for X-ray diffraction and scattering images of aliphatic polyesters. Due to recent progress in measurement methods, a large amount of image data can be obtained in a short time; therefore, machine learning methods are useful to determine the important regions for a given objective. Although techniques to visualize the judgment regions using deep learning have recently been developed, there have been few reports discussing whether such models can determine the important regions of X-ray diffraction and scattering images of polymeric materials. Herein, we demonstrate classification models based on convolutional neural networks (CNNs) for wide-angle X-ray diffraction and small-angle X-ray scattering images of aliphatic polyesters to predict the types of polymers and several crystallization temperatures. Furthermore, the judgment regions of the X-ray images used by the CNNs were visualized using the Grad-CAM, LIME, and SHAP methods. The main regions were diffraction and scattering peaks recognized by experts. Other areas, such as the beam centers were recognized when the intensity of the images was randomly changed. This result may contribute to developing important features in deep learning models, such as the recognition of structure-property relationships.

DOI： 10.1038/s41428-021-00531-w

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Mechanically tough glassy membranes with a unique confined main-chain motion are prepared by simple solvent-casting of a series of polyrotaxane derivatives. Polyrotaxanes composed of polyethylene glycol (PEG) and propionylated a-cyclodextrins are thermomoldable and highly soluble in volatile solvents (e.g., > 30 wt % in acetone). Solvent casting instantly produces freestanding transparent films with thicknesses ranging from several tens of micrometers to the submicrometer regime. The threaded rings completely inhibit the crystallization of the threading polymer. Direct mechanical measurement by bulge tests reveals that the membranes are as hard as conventional polymer glasses but extremely extensible and pinhole-free even at submicrometer thickness. The stiffness and extensibility are tunable by manipulating the number of threaded rings in a single threading chain without compromising the high processability and crystallization-inhibitory potency. Because the membrane has neither cross-linking nor additives, it can be easily recycled using the same solution process, thus reproducing the mechanical properties. The high mobility of the confined PEG in the glassy materials is confirmed by viscoelastic analysis. This mobility appears to contribute to both mechanical toughness and the high solubility of CO2 in the membrane, suggesting its potential utility as a base material for separation membranes.

DOI： 10.1021/acsapm.1c00622

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.polymer.2021.124003

Language：English   Publishing type：Research paper (scientific journal)  

Organoclay, such as organo-modified montmorillonite (MMT), is one of the potential filler candidates in the preparation of epoxy nanocomposite adhesives for automotive and civil engineering industries. However, there is no systematic research on the effect of organoclay reinforcement on its adhesion and fatigue behaviors in shear loading. Here, single-lap joints (SLJs) of stainless steel substrates bonded with epoxy/MMT nanocomposite adhesives, consisting of diglycidyl ether of bisphenol A and poly(oxypropylene) diamine with various weight contents of a commercialized MMT filler, were prepared. The dispersity of MMT and bulk mechanical properties were investigated by wide-angle X-ray scattering/diffraction, the uniaxial tensile test, and dynamic mechanical analysis. The lap shear strengths and failure modes were investigated based on the single-lap shear test, and the joint durability was examined by using the fatigue test with various shear stress levels. Through the incorporation of the MMT fillers in epoxy resins, the lap shear strengths increased from 25 to 40 MPa, the failure modes changed from adhesive failure mode to cohesive one, and the fatigue lifetimes prolonged with the addition of a small amount of MMT.

DOI： 10.1021/acsapm.1c00347

Language：English   Publishing type：Research paper (scientific journal)  

When isotropic solids are unequally stretched in two orthogonal directions, the true stress (force per actual cross-sectional area) in the larger strain direction is typically higher than that in the smaller one. We show that thiol-acrylate liquid crystal elastomers with polydomain texture exhibit an unusual tendency: The true stresses in the two directions are always identical and governed only by the area change in the loading plane, independently of the combination of imposed strains in the two directions. This feature proves a previously unidentified state of matter that can vary its shape freely with no extra mechanical energy like liquids when deformed in the plane. The theory and simulation that explain the unique behavior are also provided. The in-plane liquid-like behavior opens doors for manifold applications, including wrinkle-free membranes and adaptable materials.

DOI： 10.1126/sciadv.abe9495

Language：English   Publishing type：Research paper (scientific journal)  

The mechanical stretching behavior of the poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) triblock copolymer (87 wt% polyethylene-co-butylene (PEB), 13 wt% polystyrene (PS)) was investigated under three different stretching modes and through in situ small-angle X-ray scattering (SAXS) analysis. The strain energy density function was investigated based on the stress and stretching ratio (lambda) relationship under uniaxial, planar extension, and equi-biaxial stretching modes. As a result, the cross-effect of strain represented by the second invariants of the deformation tensor (I-2) was identified, and only the Ogden model found to fit the data. In the cyclic stretching tests, SEBS exhibited smaller hysteresis during cyclic equi-biaxial stretching compared to uniaxial stretching. In other words, the Mullins effect was found to be more obvious for uniaxial stretching than equi-biaxial stretching. The lambda and the stretching ratio obtained from the crystal planes by SAXS (lambda(SAXS)) were compared to investigate the relationship between the change in the microdomain structure and the macroscopic mechanical properties. Thus, affine deformation was found to occur in the smaller lambda region for both uniaxial and equi-biaxial stretching and deviation from affine deformation occurred for uniaxial stretching in the larger lambda region. This is because the entangled loops of PEB chains serve as cross-linking points when the films are stretched under equi-biaxial stretching.

DOI： 10.1038/s41428-021-00469-z

Language：English   Publishing type：Research paper (scientific journal)  

The complicated structure-property relationships of materials have recently been described using a methodology of data science that is recognized as the fourth paradigm in materials science. In network polymers or elastomers, the manner of connection of the polymer chains among the crosslinking points has a significant effect on the material properties. In this study, we quantitatively evaluate the structural heterogeneity of elastomers at the mesoscopic scale based on complex network, one of the methods used in data science, to describe the elastic properties. It was determined that a unified parameter with topological and spatial information universally describes some parameters related to the stresses. This approach enables us to uncover the role of individual crosslinking points for the stresses, even in complicated structures. Based on the data science, we anticipate that the structure-property relationships of heterogeneous materials can be interpretatively represented using this type of "white box" approach.

DOI： 10.1016/j.patter.2020.100135

Language：English   Publishing type：Research paper (scientific journal)  

Changes in the microphase-separated structure of the poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) triblock copolymer (13 wt % polystyrene (PS) block) were investigated during mechanical deformation. In situ synchrotron radiation small-angle X-ray scattering (SAXS)/wide-angle X-ray scattering (WAXS) measurements were successfully performed for SEBS under equi-biaxial deformation as well as under uniaxial deformation. In situ SAXS/WAXS measurements revealed changes in (1) the shape of spherical PS domains, (2) the spacing of PS domains packed in the body-centered cubic structure in the initial state, (3) their ordering, and (4) the orientation of PEB chains during deformations. In terms of the microdomain structure, affine deformation was kept below a certain strain (epsilon(d-A)), which are 4 and 1.2 for uniaxial and equi-biaxial deformation, respectively. In contrast, the ordering of the arranged PS domains decreased from the initial strain region. Above the epsilon(d-A) value, deviation from affine deformation started to occur. This deviation is related to contact of PS domains under mechanical deformation. Uniaxial stretching still showed the plane-independent behavior, while equi-biaxial stretching did not. Moreover, the epsilon(d-A) value for equi-biaxial deformation was smaller than that for uniaxial deformation and further smaller than expected. This might be because the entanglement effect was enhanced for equi-biaxial deformation. Furthermore, after contact of PS domains at around strains of 6 and 2, during uniaxial and equi-biaxial deformation, respectively, the ordering of PS domains suddenly increased with an increase in strain. It is inferred that the locked state between the PS domains and the extended PEB chains formed during deformation may have been released and repacked at a certain strain.

DOI： 10.1021/acs.macromol.0c00962

Language：English  

Polylactide (PLA) exhibits various types of crystal modifications depending on the preparation conditions, including the components. To solve the open question, a reliable calculation method for crystallinity, crystal forms, and composition in neat PLA and PLA composites was developed on the basis of temperature-dependent synchrotron wide-angle X-ray diffraction results. The relative composition of amorphous, α-form, and α’-form phases of PLA and its composites filled with halloysite nanotubes during heating was successfully obtained. It was found that only 47–56% of α’-form crystals transform into α-form crystals during a 2 °C/min heating process for PLA with a molecular weight of 54,300 g/mol. The loading of halloysite nanotubes decreases the cold crystallization and starting transition (α’ crystals transform into α-form crystals) temperatures of PLA. The crystallinity and the main diffraction peak intensity as a function of temperature were also analyzed. These results suggest that the α’-to-α form transition is a solid-solid phase transition.

DOI： 10.1038/s41428-020-0343-8

Language：English  

The strength of silica-based mechanochromic nanocomposites was improved by a novel nanocomposite synthesized by grafting poly(butyl acrylate) (PBA)-b-poly(methyl methacrylate) (PMMA) from silica nanoparticles (SiNP). Samples with different PMMA/PBA ratios were prepared to clarify the effect of the rubbery/glassy block copolymer ratios on the mechanical properties of the nanocomposites. The nanocomposites formed a face-centered cubic paracrystal-like structure and exhibited structural color. Time-resolved ultrasmall-angle X-ray scattering was carried out to investigate the structural evolution of the nanocomposites by uniaxial and biaxial mechanical deformation. Changes in color and mechanochromic properties were observed at varying distances between the particles by mechanical deformation. The nanocomposites exhibited elastic and plastic properties and became more rubber-like as the rubbery PBA weight ratio increased. The polymer brush deformed into a prolate spheroid by uniaxial stretching, and the distance between SiNP decreased in the direction perpendicular to elongation, which resulted in the color change by mechanical deformation. Moreover, the distance between SiNP increased isotropically by biaxial stretching. The polymer brush was elongated isotropically toward the in-plane direction and deformed into an oblate spheroid.

DOI： 10.1021/acs.macromol.9b02031

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English  

Hard segments of polyurethanes (PUs) are generally formed from diisocyanate and diol. Diol can be replaced with triol and thiol. These chemical structures of hard segments strongly affect not only a microphase separated structure but mechanical properties of resultant PUs. In this review, we focus on the relationship between chemical structure like symmetry and bulkiness of diisocyanate and mechanical properties of PU. Then, influence of hard segment content, incorporation of 1,1,1-trimethylol propane with trifunctional groups, and alkyldithiol was reviewed mainly on trans-1,4-bis(isocyanatomethyl) cyclohexane-poly(oxytetramethylene) glycol-based PU.

DOI： 10.1007/s10965-020-02090-9

Language：English  

Natural rubber (NR) films from various mixing ratios of large- (LRP) and small rubber particles (SRP) were prepared through latex and solution casting methods. Film-forming behaviours of the resulting films were investigated by monitoring their surface characteristics using atomic force microscopy (AFM). When the SRP portion was higher, the surface of the latex-cast films was found to be smoother as smaller particles protruded out of the surface less than larger ones did. AFM phase micrographs revealed a hexagonal shape of packed rubber particles (RPs) of the LRP film, while the RPs in the other samples were sphere-like. After aging under ambient conditions, the packed RPs were flattened while retaining their RP boundaries, creating a supporting framework within the rubber matrix. On the contrary, when the rubber film was cast from a toluene solution, the characteristic of RP boundaries disappeared and became aggregates of the membrane components on the film surface. The latex-cast films performed much better in mechanical strength than the solution-cast films did due to the destruction of the supporting framework arisen from the non-rubber components at the RP boundaries of the solution-cast film. An inhomogeneous density distribution produced by the non-rubber aggregates in the latex-cast films was observed in small angle X-ray scattering measurements.

DOI： 10.1016/j.colsurfa.2020.124571

Language：English   Publishing type：Research paper (scientific journal)  

Polyurethane elastomers (PUEs) were synthesized using trans-1,4-bis(isocyanatomethyl) cyclohexane (1,4H(6)XDI), poly(oxytetramethylene) glycol, 1,4-butanediol (BD), and 1,1,1-trimethylol propane (TMP). To control the molecular aggregation state and mechanical properties of these PUEs, hard segment contents of 20 and 30 wt% and BD/TMP ratios of 10/0 and 8/2 were chosen. Differential scanning calorimetry and small-angle X-ray scattering measurements revealed that the degree of microphase separation increased with an increase in both hard segment content and BD ratio. The Young's modulus and strain at break of the 1,4-H6XDI-based PUE were 6-20 MPa and 5-15, respectively. Incorporation of 20% TMP as a cross-linking agent into BD increased the melting temperature of the hard segment chains, that is, heat resistance, and decreased the Young's modulus. This could be due to the low density of the physical cross-linking network and the dispersion of hard segment chains in the soft segment matrix in the PUE in the presence of 20% TMP.

DOI： 10.7473/EC.2019.54.4.271

Language：English  

The scratch test was conducted for polycarbonate (PC) and poly(methyl methacrylate) (PMMA) with a load-progressive mode. Changes in the molecular aggregation structure of PC and PMMA induced by the scratch test were investigated based on polarized optical microscopic observation and small-angle X-ray scattering (SAXS) measurement. The scratching coefficient of friction (SCOF), the ratio of tangential load to normal load, of PC was much larger than that of PMMA. The width and depth of the damage on the scratch path was increased monotonically with the increase in the normal load. Hardness obtained by nanoindentation and microindentation tests were similar to those with SCOF, indicating that compression resistance mainly governs the scratch properties. The polarized optical microscopic images revealed that molecules were oriented from the edge to the center of the scratch path at a certain acute angle for both PC and PMMA. SAXS measurement revealed that microfibrils were formed along the direction of stress for PC.

DOI： 10.1016/j.polymer.2019.121773

Language：English  

The advantages of bulge testing as a method of mechanical property analysis for polymer films was described. Deformation and rupture mechanisms of glassy polymer films during bulge testing were investigated by in situ molecular aggregation structure analyses. Heat-pressed polycarbonate (PC, weight-average molecular weight (M_w) = 38k) and poly(methyl methacrylate) (PMMA, M_w = 70k and 1.2 M (PMMA-70k and PMMA-1.2 M)) films were employed as transparent glassy polymers. Evaluations of molecular aggregation structures during bulge testing were conducted by polarized high-speed camera observation and wide-angle X-ray diffraction (WAXD) measurements. PC and PMMA-1.2 M films showed a yield point in their stress-strain curves, indicating ductility, while PMMA-70k film showed brittleness. WAXD measurements revealed that the distances between the main chains slightly increased with increasing strain. With increasing film strain above the yield point, a craze-like morphology with thinning of the film was seen for the PC film, likely due to the flexible PC molecules. Although it is difficult for PMMA molecules to orient along applied stress, a transition to the thinner state with the formation of wrinkled structures occurred for the PMMA-1.2 M film above the yield point. The transition to the thinner state, which corresponds to a discontinuous decrement of the cross-section area by deformation, might be categorized as two-dimensional crazing and/or shear deformation. PMMA-70k did not show such behavior because of the small number of entanglements. The use of a small amount of films in terms of thickness and size and the capability of observation of the entire film were given as advantages of the bulge test.

DOI： 10.1016/j.polymer.2019.121632

Language：English  

The pre-vulcanized large rubber particle (LRP) and small rubber particle (SRP) latices are independently prepared to investigate their film-forming process and mechanical properties after being cast into films. The surface morphologies and roughness of both LRP and SRP films are found to be dependent on crosslink densities. The networks inside each rubber particle (RP) restrict particle deformation resulting in residual contour of RP within the film surface. For highly crosslinked RP, the collapse of the top surface of the RPs in the LRP films appears to create many “crater-like” structures within the film surfaces, while they present only protruding particles within the SRP and blend films. This seems to indicate that LRPs are easier to coalesce and form film than SRPs. Additionally, dynamic and mechanical properties and strain-induced crystallization (SIC) behaviors of the latex films, are effectively enhanced after pre-vulcanization. The pre-vulcanized LRP films perform better tensile properties and SIC than the SRP can.

DOI： 10.1002/mame.201900283

Language：English  

The deformation behavior of polythiourethane (PTU) elastomers was investigated using in situ small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and X-ray absorption fine structure (XAFS) methods. Two PTUs were prepared from poly(oxytetramethylene) glycol, 1,4-bis(isocyanatomethyl) cyclohexane, and 1,4-butanedithiol (PTU-B) or 1,5-pentanedithiol (PTU-P). The effect of methylene length of the chain extender on molecular aggregation structure of PTU during the elongation process was evaluated. SAXS measurement revealed that the spacing of hard segment domains of PTUs increased and decreased in the directions parallel and perpendicular to the elongation direction and showed a constant value of strain above 2. The strain calculated from the spacing of the hard segment domains for PTU-B was larger than that for PTU-P, suggesting that well-developed hard segment domains were formed for PTU-B. WAXD measurement showed that strain-induced crystallization of the soft segment occurred at around the strain of 2. XAFS measurement showed that at the strain of 2 or 3, atoms in the vicinity of sulfur became more ordered, which is confirmed by the decrement of the extended XAFS Debye-Waller factor. It seems reasonable from these SAXS, WAXD, and XAFS results that the hard segment domains orientation occurred for both PTUs during the deformation process, followed by strain-induced crystallization of the soft segment. In addition, PTU-B exhibits more ordered hard segment domains that maintain their aggregation structure upon uniaxial deformation in comparison with PTU-P.

DOI： 10.1021/acs.macromol.9b00982

Language：English  

Nanocomposites composed of monodisperse silica nanoparticles (SiNPs) modified with an elastic comb-shaped block copolymer brush were produced for the first time. Comb-shaped polymer brushes consisting of glassy poly(methyl methacrylate) branches and a rubbery poly(butyl acrylate) backbone were grafted from 100 nm diameter SiNPs by surface-initiated atom transfer radical polymerization. The comb-shaped polymer brush-grafted SiNPs produced self-standing films with a face-centered cubic ordered lattice structure via solvent-casting. The composite films showed rubber elasticity because of the interparticle rubbery polymer brush boundary phase. The ordered lattice exhibited significant alignment and distortion in response to the macroscopic film strain, and then reproduced the initial ordered lattice after unloading. ©

DOI： 10.1021/acs.macromol.9b00927

Language：English  

The local mechanical properties of crystalline polymer were evaluated using synchrotron radiation X-ray diffraction with 10 μm lateral resolution. A nonoriented isotactic polypropylene (iPP) film with isolated spherulites in a crystallized matrix was used as a model sample. In situ wide-angle X-ray diffraction (WAXD) measurement was performed on the iPP film using a microbeam synchrotron radiation X-ray under sinusoidal strain. The lattice spacing of the crystal planes increased and decreased in response to the applied sinusoidal strain. Local dynamic viscoelastic functions (dynamic storage and loss moduli (E′ and E″)) were calculated at room temperature from the relationship between the calculated applied stress and the response strain obtained by dynamic μ-beam WAXD measurement inside and outside of the spherulites. The E′ values inside and outside of spherulite obtained from the change in spacing of the (110) plane were 1.8 and 1.1 GPa, respectively. Furthermore, the E′ value inside of spherulite obtained from the change in spacing of the (113) plane was 6.0 GPa. These values can be explained by the deformation of crystallite, which depends on the direction of crystal planes. The results obtained here revealed that synchrotron radiation X-ray diffraction measurement gives not only structural information but also the local mechanical properties of the materials E′.

DOI： 10.1021/acsmacrolett.8b00994

Language：English  

Abstract: Polythiourethane (PTU) and polyurethane (PU) elastomers were prepared from poly(oxytetramethylene) glycol, 1,4-bis(isocyanatomethyl) cyclohexane and a dithiol or diol chain extender with two methylene numbers (tetramethylene (C4) and pentamethylene (C5)). The effect of dithiol and diol and the methylene length of the chain extenders on the microphase-separated structure and mechanical properties of PTU and PU were evaluated. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction measurements revealed that the degree of ordering of hard segment chains in PTUs is lower than that for PU elastomers. However, it was revealed from the DSC, small-angle X-ray scattering and temperature dependent dynamic viscoelasticity measurements that the degree of microphase separation in the PTUs became stronger than that for the PUs. As a result, the mechanical property of PTUs is comparable with PUs. Furthermore, the glass transition temperature for the soft segment of PTU became lower than that for PU. PTU and PU exhibited a larger degree of microphase separation and mechanical property when the chain extender was composed of a tetramethylene (C4) chain compared to a pentamethylene (C5) chain.

DOI： 10.1038/s41428-018-0148-1

Language：English  

The crystalline structures of isotactic polypropylene (iPP) thin films were investigated using grazing incident wide-angle X-ray diffraction (GIWAXD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The out-of-plane (110) reflection split with 99° inclination in the GIWAXD pattern. The film surface was covered with flat-on mother lamellae with orthogonal daughter lamellae. The cross-sectional TEM image and the fast Fourier transform-processed image showed vertically aligned daughter lamellae and cross-hatched lateral mother lamellae. Flat-on lamellae may be preferentially produced at the substrate interface, after which the mother lamellae may yield daughter lamellae from the ac plane to give vertically aligned lamellae. The daughter lamellae yield in-plane lamellae with flat-on alignment from the ac plane, resulting in the global growth of a cross-hatched lamellar structure.

DOI： 10.1038/s41428-018-0138-3

Language：English  

The relationship between the scratch behavior and molecular aggregation states of polystyrene (PS), poly(2,6-dimethyl-1,4-phenyleneoxide) (PPO), and their blends, is investigated based on differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), polarized optical microscopy (POM), and indentation and scratch tests. DSC reveals that all the PS/PPO blends show the single glass transition temperature (T_g) and the T_g monotonically increase and T_g breadth exhibits a maximum, with an increase in PPO content. Furthermore, density and intermolecular chain distance obtained by WAXD exhibits maximum and minimum values at near 50 wt% of PPO, respectively. It is evident that densification occurs by blending PS and PPO. The scratch coefficient of friction (SCOF) value of PS is the largest and PS exhibits a fish-scale pattern after scratch testing, while the SCOF value of PPO is much smaller than PS and PPO exhibits smooth groove formation. The PS50/PPO50 and PS20/PPO80 blends exhibit superior scratch and indentation resistance than PS and PPO. Damage morphology observation by POM and indentation tests reveals that molecular orientation is more restricted, and resistance against indentation increases for blends. This is due mainly to densification of the blend system.

DOI： 10.1002/macp.201800371

Language：English  

Soft denture liners and tissue conditioners are widely used for the denture patients to cushion masticatory force and condition abused tissues, respectively. This study assessed methods for the evaluation of the viscoelasticity and glass transition temperature (T_g) of the silicone permanent soft liner, acrylic permanent soft liner, and tissue conditioner. Three rheological parameters of storage modulus (E′), loss modulus (E′′), and loss tangent (tan δ), T_g, and hardness were determined using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and the Shore A0 hardness test. Five specimens were measured for each material. The time–temperature superposition principle was applied to produce master curves of E′, E′′, and tan δ for the tested materials at a reference temperature of 37 °C. The acrylic permanent soft liner and tissue conditioner exhibited viscoelastic behavior and sensitivity to frequency, especially at lower frequencies. The silicone permanent soft liner showed elastic behavior and was frequency-independent. T_g for the acrylic permanent soft liner was higher than that for the tissue conditioner, which in turn was higher than that for the silicone permanent soft liner for both DMA and DSC. In DMA, a higher frequency led to higher T_g values. A positive linear relationship was found between Shore A0 hardness and E′ values, but not E′′ and tan δ values. Shore hardness reflects elasticity, but not viscosity. The results of the present study can be used to improve methods for evaluating the viscoelasticity and T_g of soft denture liners and tissue conditioners.

DOI： 10.1007/s10266-019-00477-9

Language：English   Publishing type：Research paper (scientific journal)  

It is desirable to establish a method for evaluating mechanical properties, such as modulus and strength, of micrometer and sub-micrometer thick polymer films. Bulge tests, where bulge deformation is imposed on films by the pressure of an inert gas, are suitable for satisfying this demand. However, very few studies on polymer films exist in the literature. In this study, bulge testing equipment for in situ synchrotron radiation wide-angle X-ray diffraction (WAXD) measurements is designed and used to study the relationship between the molecular aggregation structure and the mechanical properties of a crystalline nylon 12 (Ny12) film during bulge testing. Isothermally crystallized and quenched Ny12 films exhibited stress-strain curves similar to those obtained by conventional uniaxial elongation. In situ WAXD measurements during bulge testing revealed that the lattice extension of the crystallites is clearly dependent on crystallinity. Concretely, crystallites in the isothermally crystallized film show higher elastic properties than those in the quenched one. The results of the molecular aggregation structure, including the crystal structure and the amorphous chain surrounding the crystallites, of the films during bulge deformation firstly obtained in this study must be useful for designing toughened polymer films.

DOI： 10.1039/c7sm01842h

Language：English   Publishing type：Research paper (scientific journal)  

Biocompatible and blood-compatible surface modification is urgently needed for stainless steel (SUS)-based human implant devices to avoid inflammation and biofouling. To this end, the use of polymeric surface modifiers, whose surface properties are specifically tailored, is a promising approach since this approach minimizes the impact on device's mechanical properties. However, adhesion between the device and surface modifier is relatively weak, since van der Waals forces are employed, leading to low device durability. To address this issue, this work functionalized poly(-caprolactone)-b-[poly(-chloride--caprolactone)-b-poly(2-methacryloyloxyethyl phosphorylcholine)](2) (PCL-b-(PCL-Cl-b-PMPC)(2)) with catechol groups via a nucleophilic substitution, whereby the catechol functionalization was optimized. The resultant surface modifier showed strong adhesion toward SUS surfaces, forming a smooth and uniform hydrophilic polymeric film that reduced SUS fouling (i.e., protein). Notably, no significant changes of adhesion between the SUS and thin films (thin film) were observed after immersion for 45 days in a pH 7.4 phosphate buffer solution. (c) 2017 Wiley Periodicals, Inc.

DOI： 10.1002/pola.28858

Language：English   Publishing type：Research paper (scientific journal)  

Biocompatible and blood-compatible surface modification is urgently needed for stainless steel (SUS)-based human implant devices to avoid inflammation and biofouling. To this end, the use of polymeric surface modifiers, whose surface properties are specifically tailored, is a promising approach since this approach minimizes the impact on device's mechanical properties. However, adhesion between the device and surface modifier is relatively weak, since van der Waals forces are employed, leading to low device durability. To address this issue, this work functionalized poly(ɛ-caprolactone)-b-[poly(α-chloride-ɛ-caprolactone)-b-poly(2-methacryloyloxyethyl phosphorylcholine)]₂ (PCL-b-(PCL-Cl-b-PMPC)₂) with catechol groups via a nucleophilic substitution, whereby the catechol functionalization was optimized. The resultant surface modifier showed strong adhesion toward SUS surfaces, forming a smooth and uniform hydrophilic polymeric film that reduced SUS fouling (i.e., protein). Notably, no significant changes of adhesion between the SUS and thin films (thin film) were observed after immersion for 45 days in a pH 7.4 phosphate buffer solution.

DOI： 10.1002/pola.28858

Language：English   Publishing type：Research paper (scientific journal)  

Polyurethane elastomers (PUEs) based on poly(2-ethyl-1,3-hexamethylene adipate) glycol (PEHA), poly(2,4-diethyl-1,5-pentamethylene adipate) glycol (PDEPA) and poly(2-butyl-2-ethyl-1,3-trimethylene adipate) glycol (PBETA) were synthesized with 4,4’-diphenylmethane diisocyanate (MDI) and 1,4-butane diol (BD)/1,1,1-trimethylol propane (TMP). PEHA has one primary and one secondary hydroxyl groups, but PDEPA or PBETA has two primary hydroxyl groups. The effect of low reactive secondary OH group on molecular aggregation structure and mechanical properties of the PUEs was investigated using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), dynamic viscoelastic measurement and tensile testing. The study demonstrates that PEHA-based PUE has lower cross-linking density and lower degree of microphase separation than PDEPA- and PBETA-based PUEs. As a result, PEHA-based PUE has lower dynamic storage modulus value at the rubbery plateau region and Young's modulus.

DOI： 10.1016/j.polymer.2017.03.031

Language：English   Publishing type：Research paper (scientific journal)  

Polyurethane elastomers (PUEs) containing trans-1,4-bis(isocyanatomethyl)cyclohexane (1,4-H₆XDI) have been synthesized by polymerizing 1,4-H₆XDI with poly(oxytetramethylene) glycol and 1,4-butanediol. The molecular aggregation state and mechanical properties of these PUEs have been compared with those exhibited by PUE analogues made of MDI and diols. The hard segment chains in the 1,4-H₆XDI-based PUEs are found to readily crystallize and form strong hydrogen bonds due to a high symmetry of 1,4-H₆XDI molecule. Consequently, the 1,4-H₆XDI-based PUEs exhibit well-organized hard segment domains. This leads to their generally superior mechanical properties as compared to those of the well-known MDI-based PUEs. 1,4-H₆XDI’s lack of aromatic moieties is expected to greatly enhance color stability of resulting PUEs. All the above features suggest 1,4-H₆XDI could replace MDI in a range of applications.

DOI： 10.1021/acs.macromol.6b02044

Language：English   Publishing type：Research paper (scientific journal)  

We have developed and commercialized novel polyurethane (PU) with high elasticity and durability based on a cycloaliphatic diisocyanate controlled the stereoisomer structure. The diisocyanate is called FORTIMO™ trans-1,4-bis (isocyanatomethyl) cyclohexane (1,4-H₆XDI). FORTIMO™ 1,4-H₆XDI controlled with high trans isomer structure forms a well-organized hard segment phase. Therefore a micro-phase separation structure between soft segment and hard segment phases is progressed, resulting in an improved elasticity and heat resistance of PU elastomer. In addition, the light stability for long term of this PU is excellent due to an aliphatic structure. FORTIMO™ 1,4-H6XDI based PU achieve superior elasticity and durability which was not able to be realized with the existing diisocyanate. FORTIMO™ 1,4-H₆XDI is applicable to various PUs, for example, not only thermoplastic, thermoset PU elastomers, but also water dispersed PU, micro-cellar and flexible PU foam with these advantages. This paper will describe the concept and examples of application of FORTIMO™ PU to industry.

DOI： 10.1678/rheology.45.205

Language：English   Publishing type：Research paper (scientific journal)  

Trans-1,4-bis (isocyanatomethyl) cyclohexane (1,4-H₆XDI) has been newly developed as a novel cycloaliphatic diisocyanate with a high symmetric chemical structure. The PUEs were prepared with 1,4-H₆XDI, polyesterpolyol as a long chain polyol and 1,4-butanediol (BD) as a chain extender. As the representative aromatic and aliphatic diisocyanates, 4,4'-diphenylmethane diisocyanate (MDI) and dicyclohexyl methane-4,4'-diisocyanate (H12MDI) were also used as the control. As a result, it was revealed that 1,4-H₆XDI-based PUEs achieved high elasticity such as higher impact resilience, lower compression set, improved heat resistant, and good light stability which was not able to be realized with the existing diisocyanates. The reason is explained that the hard segment chains of the 1,4-H₆XDI-based PUEs crystallized well with formation of hydrogen bonds in the PUEs due to the symmetric structure of 1,4-H₆XDI. Thus, the 1,4-H₆XDI-based PUEs can provide superior properties such as mechanical and thermal properties and excellent light stability compared to existing diisocyanate-based PUEs by rheological evaluation.

DOI： 10.1678/rheology.45.261

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The effect of molecular mobility of a pre-crystallized phase on the isothermal crystallization in the microphase-separated lamellar morphology of a strongly segregated crystalline-crystalline block copolymer, poly(ethylene glycol)-block-poly(perfluorooctylethyl acrylate) (PEG-b-PFA-C₈), was investigated. The diblock copolymer produced a microphase-separated lamellar morphology in the melt state, and the precedent crystallization of PFA-C₈ blocks provided the lamellar confinement field. The counter PEG block crystallized within the lamellar confinement field. The molecular mobility of the pre-crystallized PFA-C₈ phase was modulated by the thermal history. The structural evolution was monitored by a complementary combination of in situ time-resolved simultaneous small-angle X-ray scattering/wide-angle X-ray diffraction measurements and thermal analyses. The degree of crystallinity and the melting temperature of the PEG crystals were associated with the molecular mobility of the pre-crystallized PFA-C₈ phase. The highly packed PFA-C₈ phase (higher-ordered phase) constrained the PEG crystallization, whereas the loosely packed PFA-C₈ phase (lower-ordered phase) caused a weak restriction in the PEG crystallization to give relatively ordered PEG crystals. Subsequent crystallization in a confinement field of crystalline-crystalline block copolymers was controlled by adjusting the molecular mobility of the pre-crystallized phase.

DOI： 10.1016/j.polymer.2017.02.086

Language：English   Publishing type：Research paper (scientific journal)  

Crystallization-induced structure fluctuations in the layer thickness direction and disordering of pre-crystallized structure in crystallized microdomain structure that consist of a strongly segregated crystalline-crystalline diblock copolymer, poly(ethylene glycol)-block-poly(perfluorooctyl ethyl acrylate) (PEG-b-PFA-C₈), were investigated. The structure formation process during isothermal crystallization was monitored by in-situ time-resolved simultaneous SAXS/WAXD measurements and thermal analysis. At early stage of isothermal crystallization, three dimensional growth of the PEG lamellar crystals within lamellar microphase-separated morphology induced the volume shrinkage of PEG phase, resulting in the reduction of PEG layer thickness, increase of PFA-C₈ layer thickness and disordering of pre-crystallized PFA-C₈ crystals. At late stage of isothermal crystallization, one dimensional growth, thickening of PEG lamellar crystals induced the increase of PEG layer thickness and reduction of PFA-C₈ layer thickness. The structure fluctuation in the crystallized microdomain structure depends on the crystal growth dimension.

DOI： 10.1016/j.polymer.2016.09.024

Language：Others  

Crystallization-induced structure fluctuation of crystallized microdomain structure composed of strongly segregated crystalline-crystalline diblock copolymers

DOI： 10.1016/j.polymer.2016.09.024

Language：English   Publishing type：Research paper (scientific journal)  

We have prepared the amidinium-carboxylate salt bridge-based supramolecular network polymers from a carboxy-terminated telechelic poly(n-butyl acrylate) and a linear polyamidine having N,N′-di-substituted acetamidine group in the main chain. FTIR measurements indicated that the salt bridge was attributed to the three-dimensional network formation. Virtually, no fluidity was observed for the blend containing equimolar amounts of the carboxyl group and the amidine group, which showed a high G′ value of about 1 MPa at -5 °C. For comparison, the supramolecular network polymers crosslinked by ammonium-carboxylate salt were prepared using a linear polyethyleneimine instead of the polyamidine. The blend with equimolar amounts of the carboxyl group and the secondary amino group showed liquid-like fluidity with a G′ value of about 0.01 MPa at -5 °C, which was attributed to the fact that a certain amount of the carboxyl group remained as its free form, as evidenced by FTIR analysis.

DOI： 10.1002/pola.28082

Language：English   Publishing type：Research paper (scientific journal)  

Polyurethane studies has been still fascinating to us. In this review, current polyurethane science has been addressed focusing on structure-properties relationship of polyurethane with controlled primary strcutre, structure analysis using synchrotron radiation x-ray diffraction and scattering, development of polyurethane withself- healing properties, environment friendly polyurethanes. It is expected that polyurethane would give new brand properties by studies combining analysis based on synchrotron radiation x-ray and simulation.

Language：English   Publishing type：Research paper (scientific journal)  

Language：Others  

An effect of surface segregation of polyhedral oligomeric silsesquioxanes on surface physical properties of acrylic hard coating materials
© 2015 Elsevier Ltd. All rights reserved. An effect of surface segregation of polyhedral oligomeric silsesquioxanes (POSS) on surface physical properties was investigated. Hard coating layer with various MA8POSS loadings was prepared on a bilayer of soft layer and PMMA substrate via a UV curing process. The scratch resistance of the coating layer showed specific properties. When MA8POSS loadings in the coating layers were less than 10 wt %, the coating layers showed a great performance in scratch resistance. While MA8POSS loadings were higher than 10 wt %, the surface performance was deteriorated. This is because the outermost surface of the coating layer was covered by MA8POSS molecules when the MA8POSS loadings were higher than 10 wt %, resulting in uncompleted curing reaction caused by large steric hindrance of MA8POSS.

DOI： 10.1016/j.polymer.2015.12.037

Language：English   Publishing type：Research paper (scientific journal)  

An effect of surface segregation of polyhedral oligomeric silsesquioxanes (POSS) on surface physical properties was investigated. Hard coating layer with various MA₈POSS loadings was prepared on a bilayer of soft layer and PMMA substrate via a UV curing process. The scratch resistance of the coating layer showed specific properties. When MA₈POSS loadings in the coating layers were less than 10 wt %, the coating layers showed a great performance in scratch resistance. While MA₈POSS loadings were higher than 10 wt %, the surface performance was deteriorated. This is because the outermost surface of the coating layer was covered by MA₈POSS molecules when the MA₈POSS loadings were higher than 10 wt %, resulting in uncompleted curing reaction caused by large steric hindrance of MA₈POSS.

DOI： 10.1016/j.polymer.2015.12.037

Language：English   Publishing type：Research paper (scientific journal)  

A solvent free oxidative coupling reaction of 3-hexylthiophene (3HT) within a nanocavity is reported. It is found that 3HT can be encapsulated in nanocavities larger than 1 nm, which corresponds to the size of the molecule. In this case, the side reaction at the 4-position in 3HT is regulated.

DOI： 10.1039/c6ra23178k

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The synergistic interactions between the α-amine and the carboxylic acid in an amino acid have recently been studied as bio-based zwitterions. Here, we report a new amphiphilic polymer containing glutamic acid grafted to the end of a dodecyl polymer side chain, which contains the α-amine and the γ-carboxylic acid of the glutamic acid moiety. The polymer self-assembled into a multilayered structure in the thin film, and the glutamic acid moieties in the polymer side chains were exposed to the polymer film/water interface. Annealing the sample enhanced the formation of a well-oriented lamellar structure in the films. Due to the presence of the glutamic acid moieties at the interface, the surface charge was controllable by pH in buffer solutions, resulting in zwitterionic character at neutral pH. It has been widely accepted that zwitterionic surfaces can exhibit non-fouling for proteins. Interestingly enough, the polymer film showed charge-selective protein adsorption since the synergistic interaction between the α-amine and the γ-carboxylic acid was weaker than conventional amino acid-based zwitterionic systems. This is due to the separated state of the functional groups by a three carbon spacer.

DOI： 10.1039/c5py00783f

Language：Others  

pH-Responsive and selective protein adsorption on an amino acid-based zwitterionic polymer surface
© The Royal Society of Chemistry. The synergistic interactions between the α-amine and the carboxylic acid in an amino acid have recently been studied as bio-based zwitterions. Here, we report a new amphiphilic polymer containing glutamic acid grafted to the end of a dodecyl polymer side chain, which contains the α-amine and the γ-carboxylic acid of the glutamic acid moiety. The polymer self-assembled into a multilayered structure in the thin film, and the glutamic acid moieties in the polymer side chains were exposed to the polymer film/water interface. Annealing the sample enhanced the formation of a well-oriented lamellar structure in the films. Due to the presence of the glutamic acid moieties at the interface, the surface charge was controllable by pH in buffer solutions, resulting in zwitterionic character at neutral pH. It has been widely accepted that zwitterionic surfaces can exhibit non-fouling for proteins. Interestingly enough, the polymer film showed charge-selective protein adsorption since the synergistic interaction between the α-amine and the γ-carboxylic acid was weaker than conventional amino acid-based zwitterionic systems. This is due to the separated state of the functional groups by a three carbon spacer.

DOI： 10.1039/C5PY00783F

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1166/sam.2015.1913

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1295/koron.2014-0074

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1295/koron.2014-0074

Language：English  

Improvement of the low-temperature property of aliphatic polycarbonate glycols-based polyurethane elastomers
Structure-property relationship of polyurethane elastomers (PUEs) based on aliphatic carbonate glycols (PCglycols) with various molecular weights (HO-[(CH2)mOC(=O)O]n-(CH2)m-OH, m = 3 and 6, Mn= 1000-3000) were investigated to improve their low-temperature property. Differential scanning calorimetry (DSC) measurement revealed that the glass transition temperature (Tg) of the soft segment in the PUEs decreased ca. 10-25oC and crystallized hard segment exhibited larger heat of fusion with increasing molecular weight of the PC-glycol. This trend clearly implies that the degree of microphase separation of the PUEs became stronger with an increase in molecular weight of the PC-glycol. In the tensile testing, Young's modulus and tensile strength increased with increase in the degree of microphase separation. In other words, an increase in molecular weight of the PC-glycol gives the PUEs bearing lower Tgand superior mechanical properties.

DOI： 10.1166/sam.2015.1913

Language：English   Publishing type：Research paper (scientific journal)  

Poly(3-hexylthiophene) (P3HT) is an important basic material that is widely used in p-type semiconductor devices for organic solar cells and transistors. time. However, the change is dramatically suppressed in comparison with the initial reaction. This supports that there is polymer adsorption on the ferric chloride particles that regulates formation of the radical cation on the 3HT. In short, the adsorbed polymer appears to poison the catalytic behavior. To clarify the effect of solvent on the polymerization, researchers replaced chloroform with hexane and carried out the reaction under similar conditions. The polymerization is initiated when two radical cations react. A pair of protons departs at the extended part of the dimer to form a neutral structure. Another radical cation is then generated at the end of the extended polymer chain due to reduction of Fe(II), propagating the reaction. Through this reaction, a polymer with high molecular weight is formed.

DOI： 10.1002/pola.27720

Language：English   Publishing type：Research paper (scientific journal)  

Structure-property relationship of polyurethane elastomers (PUEs) based on aliphatic carbonate glycols (PCglycols) with various molecular weights (HO-[(CH₂)_mOC(=O)O]n-(CH₂)_m-OH, m = 3 and 6, M_n = 1000-3000) were investigated to improve their low-temperature property. Differential scanning calorimetry (DSC) measurement revealed that the glass transition temperature (T_g) of the soft segment in the PUEs decreased ca. 10-25 ^oC and crystallized hard segment exhibited larger heat of fusion with increasing molecular weight of the PC-glycol. This trend clearly implies that the degree of microphase separation of the PUEs became stronger with an increase in molecular weight of the PC-glycol. In the tensile testing, Young's modulus and tensile strength increased with increase in the degree of microphase separation. In other words, an increase in molecular weight of the PC-glycol gives the PUEs bearing lower T_g and superior mechanical properties.

DOI： 10.1166/sam.2015.1913

Language：English   Publishing type：Research paper (scientific journal)  

A new total internal reflection (TIR) Raman microscope that can be used for adhesion testing based on the Johnson-Kendall-Roberts (JKR) theory was developed. The angle and the focus of the laser beam can be accurately controlled by observing the image of the laser spot on a CCD camera in the spectrometer. As a result, strong Raman signals were obtained. It was observed that the depolarization ratio of polymer brushes changes with the compressive force. This equipment is useful for the analysis of the interface and the anisotropic structure of polymer thin films.

DOI： 10.1295/koron.2015-0043

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Synthesis of zinc oxide nanoparticles in the core of reverse micelles of poly(methyl methacrylate)-block-poly(acrylic acid) (PMMA-b-PAA) in toluene, and succeeding hybridization with poly(methyl methacylate) (PMMA) to fabricate transparent hybrid films was investigated. Inclusion of a ZnO precursor into the cores of the reverse micelles formed in toluene was carried out by addition of diethyl zinc, and heating the resulting solution to 125°C in an autoclave to form ZnO that formed crystals. Fabrication of ZnO/PMMA hybrid films by a casting method using a mixed solution of the reverse micelles and PMMA resulted in low transparency films due to aggregation of ZnO nanoparticles during film forming. Freeze drying of the reverse micelle solution to prepare a ZnO/PMMA hybrid powder and succeeding hybridization with PMMA by hot-pressing at 150°C and 20 MPa gave highly transparent ZnO/PMMA hybrid films, refractive indexes of which were coincident with calculated values. TEM images showed small domains of PMMA and domains containing ZnO nanoparticles.

DOI： 10.1295/koron.71.644

Language：Japanese   Publishing type：Research paper (scientific journal)  

ポリウレタンエラストマー中でハードセグメントを構成する4,4’-ジフェニルメタンジイソシアネート(MDI)および1,4-ブタンジオール(BD)からなるモデルポリウレタンの結晶化挙動を評価した。試料として、MDI、BD、1,1,1-トリメチロールプロパン(TMP)およびポリオールを用いて、MDI-BD連鎖のBDをTMPあるいはポリオールで代替するように配合比を変化させて合成した。TMPおよびポリオールの含有率が高くなると、MDI-BD連鎖の結晶の融点(Tm)はそれぞれ低下および上昇した。また、ポリオールの分子量の低下および他の使用によりTmは低下した。これらの結果より、繰り返し数が大きいMDI-BD連鎖は結晶の形成にやや阻害するほど剛直で自身の凝集力が高いこと、適切な第3成分を組み込むことで分子鎖が良好にパッキングされた平衡状態に近い結晶を調製可能であることが明らかとなった。

DOI： 10.1295/koron.71.608

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/pj.2014.24

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/pj.2014.24

Language：Others  

Crystallization behavior of hard segment in polyurethane elastomers
The crystalline hard segment models of segmented polyurethane elastomers are made of 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD). Here we investigate the crystalline behavior of polyurethane that in addition contain 1,1,1-trimethylol propane (TMP), poly(oxytetramethylene) glycol (PTMG), and polyethylene glycol (PEG). The melting points (Tm) of crystallized MDI-BD units decreased with increasing TMP contents and increased with increasing PTMG contents, respectively. A decrease in molecular weight of PTMG and incorporation of PEG decreased Tm. These results indicate that incorporation of a third component would cause to form the well-ordered crystal being closed to equilibrium state.

DOI： 10.1295/koron.71.608

Language：Others  

Microphase-separated structure and dynamic viscoelastic properties of polyurethanes elastomers prepared at various temperatures and cross-linking agent contents
The relationship between a microphase-separated structure and dynamic viscoelastic properties of polyurethane elastomers (PUEs) prepared at various temperatures and cross-linking agent contents were investigated. The PUEs were synthesized with poly(oxytetramethylene) glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) and a mixture of BD and 1,1,1-trimethylol propane (TMP) by a prepolymer method. The PUEs are in the strong-segregation limit. The microphase-separated structure was investigated using Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS) and atomic force microscope (AFM). The extent of microphase separation of the PUEs became stronger and weaker with increases in curing temperature and trifunctional TMP content, respectively. The consistent results obtained in this study would be quite helpful to design the desirable PUEs. ? 2014 The Society of Rheology, Japan.

DOI： 10.1678/rheology.42.143

Language：English   Publishing type：Research paper (scientific journal)  

ABA-type triblock copolymers (PEOxz-PTHF-PEOxz) composed of poly(tetrahydrofuran) (PTHF) and poly(2-ethyl-2-oxazoline) (PEOxz) were synthesized by cationic sequential polymerization. Differential scanning calorimetry and wide-angle X-ray diffraction analyses revealed that PEOxz-PTHF-PEOxzs produced a microphase separation structure, which consisted of a partially crystallized amorphous PTHF phase containing PEOxz chains on both ends. Tensile testing showed that PEOxz-PTHF-PEOxz exhibited tough mechanical properties that differed from those of the brittle PTHF homopolymer. Thus, it was suggested that the amorphous PTHF/PEOxz phase played a role in physically cross-linking the moieties via entanglement, resulting in a PEOxz-PTHF-PEOxz material with tough mechanical properties and the ability to be cold-drawn.

DOI： 10.1038/pj.2013.39

Language：English  

Physical properties of poly(tetrahydrofuran)-block-poly(2-ethyl-2- oxazoline) triblock copolymer
ABA-type triblock copolymers (PEOxz-PTHF-PEOxz) composed of poly(tetrahydrofuran) (PTHF) and poly(2-ethyl-2-oxazoline) (PEOxz) were synthesized by cationic sequential polymerization. Differential scanning calorimetry and wide-angle X-ray diffraction analyses revealed that PEOxz-PTHF-PEOxzs produced a microphase separation structure, which consisted of a partially crystallized amorphous PTHF phase containing PEOxz chains on both ends. Tensile testing showed that PEOxz-PTHF-PEOxz exhibited tough mechanical properties that differed from those of the brittle PTHF homopolymer. Thus, it was suggested that the amorphous PTHF/PEOxz phase played a role in physically cross-linking the moieties via entanglement, resulting in a PEOxz-PTHF-PEOxz material with tough mechanical properties and the ability to be cold-drawn. Copyright ? 2013 The Society of Polymer Science, Japan.

DOI： 10.1038/pj.2013.39

Language：English  

NO₂-sensing properties of porous In₂O₃ (pr-In₂O₃) powders prepared by ultrasonic-spray pyrolysis employing polymethylmethacrylate (PMMA) microspheres as a template has been investigated in this study. The PMMA microspheres were synthesized in water by ultrasonic-assisted emulsion polymerization employing methyl methacrylate monomer, sodium lauryl sulfate as a surfactant and ammonium persulfate as an initiator. The PMMA microspheres synthesized was quite uniform and the particle size was ca. 60.2 nm (measured by dynamic light scattering). The microstructure of pr-In₂O₃ powders prepared was largely dependent on the kind of In₂O₃ sources. The pr-In₂O₃ which was prepared from In(NO₃)₃ as an In ₂O₃ source (pr-In₂O₃(N)) consisted of submicron-sized spherical particles with welldeveloped spherical mesopores (several tens of nanometers in pore diameter) and each oxide wall among pores was constructed with meso-sized In₂O₃ particles connected continuously. On the other hand, the pr-In₂O₃ which was prepared from InCl₃ as an In₂O₃ source (pr-In2 O₃(Cl)) was composed of a large number of dispersed meso-sized particles and a few submicron-sized dense spherical particles. In contrast, the morphology of conventional In₂O₃ powder (c-In ₂O₃) prepared by ultrasonic-spray pyrolysis of PMMAfree In(NO₃)3 aqueous solution as a reference was relatively dense and roughly spherical with a diameter of ca. 100-700 nm. The responses to 1.0 and 10ppm NO₂ of pr-In₂O₃ sensors in air were much larger than those of a c-In₂O₃(N) sensor in the temperature range of less than 250°C and 300°C, respectively. In addition, the response and recovery speeds of both the pr-In₂O ₃ sensors were much faster than those of the c-In₂O ₃(N) sensor, because of the well-developed porous structure of the pr-In₂O₃ sensors.

DOI： 10.1016/j.snb.2013.02.090

Language：English  

Influence of side group contents of polycarbonate glycol on aggregation structures & mechanical properties of polyurethane elastomers

Language：English   Publishing type：Research paper (scientific journal)  

Magnetic and magnetotransport properties of pyromellitic dianhydride-4,4′-oxydianiline polyimide-Co granular thin films prepared by vapor deposition polymerization are investigated. The prepared sample is composed of Co particles with diameters of 2-3 nm homogeneously dispersed in a denatured polyimide matrix. The temperature dependence of the resistivity closely follows the T - 1 / 2 law, suggesting that the dominant conduction mechanism is tunneling between metallic granules embedded in the insulating polyimide matrix. The magnetoresistances at 300 and 90 K are 2.6 and 3.0, respectively. The results indicate that polyimide is a promising material for organic spintronics.

DOI： 10.1063/1.4768783

Language：English   Publishing type：Research paper (scientific journal)  

Magnetic and magnetotransport properties of pyromellitic dianhydride-4,4'-oxydianiline polyimide-Co granular thin films prepared by vapor deposition polymerization are investigated. The prepared sample is composed of Co particles with diameters of 2-3 nm homogeneously dispersed in a denatured polyimide matrix. The temperature dependence of the resistivity closely follows the T-1/2 law, suggesting that the dominant conduction mechanism is tunneling between metallic granules embedded in the insulating polyimide matrix. The magnetoresistances at 300 and 90K are 2.6% and 3.0%, respectively. The results indicate that polyimide is a promising material for organic spintronics. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768783]

DOI： 10.1063/1.4768783

Language：English   Publishing type：Research paper (scientific journal)  

Dispersion of fullerene, C ₆₀, by addition of polymethacrylate dispersant in methyl methacrylate (MMA) and incorporation of C ₆₀ into poly(methyl methacrylate) (PMMA) were investigated. Copolymers synthesized by radical copolymerization of MMA and 2-naphthyl methacrylate (NMA), poly(MMA-co-NMA), effectively dispersed C ₆₀ in MMA to form clusters of 20 nm. In these cases, addition of minimal 110 naphthyl groups per unit C ₆₀ molecule afforded to give clusters with minimum of 20 nm sizes. Furthermore, block copolymers, poly(MMA-b-NMA) with MMA/NMA mole ratio from 12:1 to 20:1, also efficiently dispersed C ₆₀ to give formation of clusters of 20 nm size by addition of minimal 40 naphthyl groups per unit C ₆₀ molecule, which was corresponding to approximate nine layers of naphthyl group in block copolymer adsorbed on the surface of the cluster. Hybrid films of C ₆₀/PMMA, prepared by casting of C ₆₀-dispersed solution containing PMMA, exhibited absorbance at 400 nm linearly increased with C ₆₀ content.

DOI： 10.1007/s00396-012-2707-x

Language：English  

The effect of cross-linking density and dangling chains on surface molecular mobility of network polyurethanes
Chemically cross-linked polyurethanes (PUs) were synthesized with two different cross-linking densities and dangling chain concentrations to understand the difference between the molecular mobility of the bulk and free surface based on dynamic viscoelastic properties, lateral force microscopy (LFM) and scanning viscoelasticity microscopy (SVM) measurements. The PUs were synthesized from poly(oxypropylene) triol (PPT; M n = 3000) and tolylene-2,4-diisocyanate (TDI) with a formulation ratio (= [NCO]/[OH]) of 0.85 and 1.20. The former PU has a lightly cross-linked structure with dangling chains, and the latter one has a densely cross-linked structure with allophanate groups and without dangling chains. The α-relaxation process, associated with glass transition of the PPT chains for the bulk and surface, was observed for both PUs in dynamic viscoelastic properties and lateral force microscopy measurements, respectively. The temperature region, at which the α-relaxation process was observed, for the surface was lower and broader in comparison with bulk and the trend was more obvious for the PU with dangling chains. These results can be explained well with the existence of dangling chains and their segregation at the top surface because of lower conformational entropy. ? 2012 The Royal Society of Chemistry.

DOI： 10.1039/c2py20149f

Language：English   Publishing type：Research paper (scientific journal)  

Dispersion of fullerene, C-60, by addition of polymethacrylate dispersant in methyl methacrylate (MMA) and incorporation of C-60 into poly(methyl methacrylate) (PMMA) were investigated. Copolymers synthesized by radical copolymerization of MMA and 2-naphthyl methacrylate (NMA), poly(MMA-co-NMA), effectively dispersed C-60 in MMA to form clusters of 20 nm. In these cases, addition of minimal 110 naphthyl groups per unit C-60 molecule afforded to give clusters with minimum of 20 nm sizes. Furthermore, block copolymers, poly(MMA-b-NMA) with MMA/NMA mole ratio from 12:1 to 20:1, also efficiently dispersed C-60 to give formation of clusters of 20 nm size by addition of minimal 40 naphthyl groups per unit C-60 molecule, which was corresponding to approximate nine layers of naphthyl group in block copolymer adsorbed on the surface of the cluster. Hybrid films of C-60/PMMA, prepared by casting of C-60-dispersed solution containing PMMA, exhibited absorbance at 400 nm linearly increased with C-60 content.

DOI： 10.1007/s00396-012-2707-x

Language：English   Publishing type：Research paper (scientific journal)  

Chemically cross-linked polyurethanes (PUs) were synthesized with two different cross-linking densities and dangling chain concentrations to understand the difference between the molecular mobility of the bulk and free surface based on dynamic viscoelastic properties, lateral force microscopy (LFM) and scanning viscoelasticity microscopy (SVM) measurements. The PUs were synthesized from poly(oxypropylene) triol (PPT; M _n = 3000) and tolylene-2,4-diisocyanate (TDI) with a formulation ratio (= [NCO]/[OH]) of 0.85 and 1.20. The former PU has a lightly cross-linked structure with dangling chains, and the latter one has a densely cross-linked structure with allophanate groups and without dangling chains. The α-relaxation process, associated with glass transition of the PPT chains for the bulk and surface, was observed for both PUs in dynamic viscoelastic properties and lateral force microscopy measurements, respectively. The temperature region, at which the α-relaxation process was observed, for the surface was lower and broader in comparison with bulk and the trend was more obvious for the PU with dangling chains. These results can be explained well with the existence of dangling chains and their segregation at the top surface because of lower conformational entropy.

DOI： 10.1039/c2py20149f

Language：English   Publishing type：Research paper (scientific journal)  

Polyurethane elastomers (PUEs) were prepared with poly(oxytetramethylene) glycol (M_n=2000), 4,4′-diphenylmethane diisocyanate, 1,4-butanediol (BD) and 1,1,1-trimethylol propane (TMP) by a prepolymer method. To evaluate the effect of curing temperature and the ratio of curing and crosslinking agents ((BD/TMP)=(10/0 and 8/2)(wt/wt)) on deformation behavior, four different samples were prepared. In the small-angle X-ray scattering (SAXS) profile for the PUEs prepared at 120 °C, a four-point pattern was observed with the preferred tilt being produced by local torques exerted within the strained soft segments from the initial deformation. At near failure strains, strong meridional scattering appeared and the four-point pattern disappeared. In contrast, the PUEs at 80 °C produced meridional scattering through the deformation. As the microdomain structure of the PUEs prepared at 120 and 80 °C initially possessed cylinder- and sphere-like structures, respectively, the cylinder-like structure might have produced the four-point pattern. Obvious changes in interdomain spacing of PUEs at 120 °C during the deformation process were observed in comparison with the spacing at 80 °C. This was due mainly to the formation of a well-developed, networked, cylinder-like microdomain structure. Strain-induced crystallization of the soft-segment chains evaluated by wide-angle X-ray diffraction results was also consistent with the results from SAXS.

DOI： 10.1038/pj.2011.48

Language：English   Publishing type：Research paper (scientific journal)  

Mechanical properties of thermoplastic polyurethane elastomers based on either polyether or polycarbonate (PC)-glycols, 4,4'-dipheylmethane diisocyanate (1,1'-methylenebis(4-isocyanatobenzene)), 1,4-butanediol, were controlled by restriction of crystallization of polymer glycols. For the polyether glycol based-polyurethane elastomers (PUEs), poly(oxytetramethylene) glycol (PTMG), and PTMG incorporating dimethyl groups (PTG-X) and methyl side groups (PTG-L) were employed as a polymer glycol. For the PC-glycol, the randomly copolymerized PC-glycols with hexamethylene (C₆) and tetramethylene (C₄) units between carbonate groups with various composition ratios (C₄/C₆ = 0/100, 50/50, 70/30 and 90/10) were employed. The degree of microphase separation and mechanical properties of both the PUEs were investigated using differential scanning calorimetry, dynamic viscoelastic property measurements and tensile testing. Mechanical properties could be controlled by changing the molar ratio of two different monomer components.

DOI： 10.3390/ma3125097

Language：English   Publishing type：Research paper (scientific journal)  

The morphology of poly(styrene-b-ethylene-r-butylene) (SEB) and poly(styrene-b-ethylener-butylene-b-styrene) (SEBS) thin films annealed both above (165 °C) and below (125 °C) the bulk order-order transition temperatures (OOT) (∼140 °C) was characterized with grazing incidence small-angle X-ray scattering (GISAXS), dynamic secondary ion mass spectrometry (d-SIMS), and atomic force microscopy (AFM). The SEBS thin film morphology is always spherical, regardless of film thickness or annealing temperature, leading us to conclude that the OOT for films up to five layers of spheres is depressed by at least 10 °C relative to the bulk. In contrast, the SEB film morphology at both 125 and 165 °C is always cylindrical, except when the film thickness is less than t_cyl, a monolayer of cylinders. For SEB film thicknesses, t, less than t_cyl at 165 °C either a partial or full monolayer of spheres forms (thickness t_sPh) with coexistence of patches of spheres and cylinders when t_sph < t < t _cyl. Thus, we conclude that the OOT for SEB film thickness between t_cyl and 5t_cyl is increased by at least 20 °C over that of the bulk. This complex phase behavior can be understood qualitatively by considering two small contributions to the free energy f per block copolymer chain in the films: (1) an increase in/due to packing frustration and (2) a decrease in f due to the entropy of chain ends near the block copolymer film surfaces. The SEBS has no chain ends near the surface, and we propose that the larger packing frustration of SEBS chains in the square Wigner-Seitz cells of the cylinder monolayer, and the surface half-layers in thicker films, leads to the stabilization of the spherical morphology, which has a smaller packing frustration in the monolayer and surface half-layers. The SEB cylinders and sphere monolayers have the same packing frustration as those of the SEBS, but the contribution of the added entropy of chain ends near the surface is larger for the cylinders than for the spheres, more than offsetting the effect of packing frustration and thus stabilizing the cylindrical morphology at temperatures above the OOT.

DOI： 10.1021/ma1001194

Language：English   Publishing type：Research paper (scientific journal)  

The morphology of poly(styrene-b-ethylene-r-butylene) (SEB) and poly(styrene-b-ethylene-r-butylene-b-styrene) (SEBS) thin films annealed both above (165 degrees C) and below (125 degrees C) the bulk order order transition temperatures (OOT) (similar to 140 degrees C) was characterized with grazing incidence small-angle X-ray scattering (GISAXS), dynamic secondary ion mass spectrometry (d-SIMS), and atomic force microscopy (AFM). The SEBS thin film morphology is always spherical, regardless of film thickness or annealing temperature, leading us to conclude that the OOT for films up to five layers of spheres is depressed by at least 10 degrees C relative to the bulk. In contrast, the SEB film morphology at both 125 and 165 degrees C is always cylindrical, except when the film thickness is less than t(cyl), a monolayer of cylinders. For SEB film thicknesses, t, less than t(cyl) at 165 degrees C either a partial or full monolayer of spheres forms (thickness t(sph)) with coexistence of patches of spheres and cylinders when t(sph) < t < t(cyl). Thus, we conclude that the OOT for SEB film thickness between t(cyl) and 5t(cyl) is increased by at least 20 degrees C over that of the bulk. This complex phase behavior can be understood qualitatively by considering two small contributions to the free energy f per block copolymer chain in the films: (1) an increase in f due to packing frustration and (2) a decrease in f due to the entropy of chain ends near the block copolymer film surfaces. The SEBS has no chain ends near the surface, and we propose that the larger packing frustration of SEBS chains in the square Wigner-Seitz cells of the cylinder monolayer, and the surface half-layers in thicker films, leads to the stabilization of the spherical morphology, which has a smaller packing frustration in the monolayer and surface half-layers. The SEB cylinders and sphere monolayers have the same packing frustration as those of the SEBS, but the contribution of the added entropy of chain ends near the surface is larger for the cylinders than for the spheres, more than offsetting the effect of packing frustration and thus stabilizing the cylindrical morphology at temperatures above the OOT.

DOI： 10.1021/ma1001194

Language：English   Publishing type：Research paper (scientific journal)  

A series of eight aliphatic polycarbonate (PC) glycols with various methylene numbers (HO-[(CH(2))(m)OC(=O)O](n)-(CH(2))(m)-OH,m = 3, 4, 5, 6, 7, 8, 9, and 10) were employed its a soft segment for a synthesis of polyurethane elastomers (PUEs). First of all, viscosity, glass transition temperature, inciting point, and crystalline structure of these new PC-glycols were investigated The PC-glycol-based PUEs were synthesized using the PC-glycols, 4.4'-diphenylmethane dusocyanate, and 1,4-butanediol by it one-shot method. Differential scanning calorimetry and small-angle X-ray scattering measurements revealed that the degree of microphase separation of the PC-glycol-based PUEs became first weaker and then stronger with increasing number of methylene groups of PC-glycols. The threshold carbon number for the degree of microphase separation was six In the tensile testing, Young's modulus of the PUEs decreased and increased with an increase in the methylene number, which can be explained by the degree of microphase separation Tensile strength and elongation at break of the PC-glycol-based PUEs increased and decreased with increasing the number of methylene groups These results are associated with the case of packing of the PC-glycol chains.

DOI： 10.1021/ma901317t

Language：English   Publishing type：Research paper (scientific journal)  

A series of eight aliphatic polycarbonate (PC) glycols with various methylene numbers (HO-[(CH₂)_mOC(=O)O]₂) _m-OH, m = 3, 4, 5, 6, 7, 8, 9, and 10) were employed as a soft segment for a synthesis of polyurethane elastomers (PUEs). First of all, viscosity, glass transition temperature, melting point, and crystalline structure of these new PC-glycols were investigated. The PC-glycol-based PUEs were synthesized using the PC-glycols, 4,4′-diphenylmethane diisocyanate, and 1,4-butanediol by a one-shot method. Differential scanning calorimetry and small-angle X-ray scattering measurements revealed that the degree of microphase separation of the PC-glycol-based PUEs became first weaker and then stronger with increasing number of methylene groups of PC-glycols. The threshold carbon number for the degree of microphase separation was six. In the tensile testing, Young's modulus of the PUEs decreased and increased with an increase in the methylene number, which can be explained by the degree of microphase separation. Tensile strength and elongation at break of the PC-glycol-based PUEs increased and decreased with increasing the number of methylene groups. These results are associated with the ease of packing of the PC-glycol chains.

DOI： 10.1021/ma901317t

Language：English   Publishing type：Research paper (scientific journal)  

Thermoplastic polyurethane (TPU) was thin film coated on polyamide 6 (PA6) fibers by the reactive bulk and solution coating techniques. The thickness of the coating was 40 mu m for the reactive bulk coating technique and 20 mu m for the solution coating. The increase in crystallinity, the formation of the interface interaction region and the entry of TPU thin film coating into the micro-cracks under tensile stress resulted in the increase of strength as well as elongation of the TPU coated PA6 fibers. The microphase separated-structure and the orientation of the hard segment domains of the TPU thin film coating on the PA6 fiber surface had an impact on the force alignment of the PA6 fiber when under a mechanical stress. The hard segment domains of the TPU thin film which was prepared by a solution coating technique showed better alignment to the deformation force direction compared to the reactive bulk based one. This led to better mechanical strength of the former based TPU coated PA6 fiber. The TPU is a soft material and the improvement of mechanical property with same should be specially noted. So an understanding of both type of coating techniques is very useful in various industrial applications of PA6 fibers.

DOI： 10.2115/fiber.65.236

Language：English   Publishing type：Research paper (scientific journal)  

Spherulite size graded polyurethane elastomers (PUEs) were prepared using a mold with a temperature gradient from different polymer glycols, 4,4'-diphenylmethane diisocyanate (MDI) and a mixture of 1,4-butanediol (BD), and 1,1,1-trimethylol propane (TMP) as a curing agent by a prepolymer method. The used polymer glyocols were poly(oxytetramethylene)glycol (PTMG, M(n) = 2000), poly(ethylene adipate)glycol (PEA, M(n) = 2000), and poly(hexa in ethylene adipate)glycol (PHA, M(n) = 2000). The effect of polyether and polyester glycols and the temperature gradient on the micro-aggregation structure and mechanical properties were studied by polarized optical microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, micro-hardness test, pulsed nuclear magnetic resonance spectroscopy, and tensile test. The prepared PUEs had spherulite size graded super-structure. Spherulite sizes of the PUEs depended significantly on the temperature gradient of the mold. Spherulite of the PUEs in contact with the mold at low temperature was significantly smaller and more dense than that contacting the mold at high temperature. The spherulite diameter of PTMG-, PEA-, and PHA-PUEs changed from 12.6 to 16.3 mu m, 8.4 to 15.6 mu m, and 10.4 to 16.0 mu m, respectively from the lower temperature side (LTS) toward the higher temperature side. In contrast, the number of spherulites became sparser toward the higher one. The glass transition temperature (T(g)) of PTMG-, PEA-, and PHA-based PUEs elevated from -55.3 degrees C, -19.0 degrees C and -33.8 degrees C at the LTS to -48.6 degrees C, -17.8 degrees C and -32.8 degrees C at the HTS, respectively. T(g) of all PUEs exhibited elevation from the LTS toward the higher one. This result associated with the strong microphase separation of the LTS. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1454-1461, 2009

DOI： 10.1002/app.30047

Language：English   Publishing type：Research paper (scientific journal)  

Highly hydrophilic polyurethane elastomers (PUEs) were synthesized from 1,2-bis(isocyanate) ethoxyethane (TEGDI), poly(ethylene oxide-co-propylene oxide) copolyol (EOPO) and 1,4-butane diol/1,1,1-tri-methylol propane (75/25) (wt/wt) by a prepolymer method. 4,4'-Diphenylmethane diisocyanate (MDI)-based PUEs were synthesized as a control as well. Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) measurements revealed that the degree of microphase separation of the TEGDI-based PUEs was much weaker than for the MDI-based PUEs. Young's modulus and elongation at break of the TEGDI-based PUEs were quite lower and larger than for the MDI-based PUEs, respectively. This is due to quite weak cohesion force of the hard segment chains in the TEGDI-based PUEs. The degree of swelling of the TEGDI-based PUEs was five times larger than for the MDI-based one. This is associated with the hydrophilic nature of TEGDI and weak cohesion force in the TEGDI-based PUEs. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2009.05.030

Language：English   Publishing type：Research paper (scientific journal)  

The effect of side methyl and dimethyl groups of the soft segment component on the microphase-separated structure and mechanical properties of polyurethane elastomers (PUEs) was investigated. Poly(oxytetramethylene) glycol (PTMG), and PTMG incorporating dimethyl groups (PTG-X) and methyl side groups (PTG-L) were used as a polymer glycol, which forms a soft segment in the PUEs. The PUEs were synthesized with 4,4'-dipheylmethane diisocyanate [1,1'-methylenebis(4-isocyanatobenzene)], 1,4-butane diol, and 1,1,1-trimethylol propane by a prepolymer method. The degree of microphase separation of the PUEs became weaker with increasing side group content in polymer glycols. Dynamic viscoelastic properties measurement showed reorganized-crystallization and melting of the soft segment for the PUEs based on PTMG, PTG-L, and PTG-X with a lower content of the side groups, but not for a PTG-L and PTG-X with higher content of the side groups. Tensile testing revealed that increasing methyl group concentration made the PUEs soften and weaken. The PTMG-based PUEs obviously exhibited strain-induced crystallization of the soft segment chains during elongation process. In contrast, for the PTG-L and PTG-X-based PUEs, crystallinity decreased with increasing side group content, and the PUEs with PTG-L and PTG-X with highest methyl group content did not crystallize even at a large strain.(C) 2008 Wiley Periodicals, Inc.

DOI： 10.1002/polb.21540

Language：English  

Molecular mobility of soft segment of polyurethane elastomers under elongation
In this study, we investigated molecular mobility of a soft segment in the poly(oxypropylene) glycol (PPG), 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butane diol (BD)-based polyurethane elastomers (PUE) with and without elongation by dynamic viscoelastic property measurement and pulse nuclear magnetic resonance (NMR) measurement. The peak position of the loss tangent (tand) curves shifted to the lower temperature region with increasing elongation. In the pulse NMR measurement, the long spin-spin relaxation time (T2) component appeared at -18.0(ε=0) and -26.0°C(ε=1. 5), respectively, with increasing temperature. Since this temperature seems to be related to the glass transition temperature (Tg) of the soft segment in the PUE, it is likely to consider that the Tg decreased with increasing strain. These results might be attributed that the size of cooperative motion during the glass transition decrease due to the orientation of the soft segment, and the soft segment phase approach to a pure phase on account of the extraction of the hard segment from the soft segment phase. ? 2008 American Institute of Physics.

DOI： 10.1063/1.2964568

Language：English   Publishing type：Research paper (scientific journal)  

The effects of the molecular aggregation structure on the rheological properties of thermoplastic polyurethane (TPU) were investigated. The TPU was composed of poly( (tetramethylene adipate)-co-(hexamethylene adipate)) glycol as the soft segments, 4,4-diphenyl methane diisocyanate and 1,4-butanediol as the hard segments. The TPU sheets prepared by injection molding were annealed at various temperatures from 23 to 120 degrees C to vary the molecular aggregation structure. Glass transition temperature of the soft segment and melting points of the hard segment domains of the TPUs decreased and increased, respectively, with increasing annealing temperature. The results of DSC, solid-state NMR spectroscopy and dynamic viscoelastic measurements revealed that the degree of micro-phase separation of the TPUs becomes stronger with increasing annealing temperature due to the progress of formation of well-organized hard segment domains. The dynamic temperature sweep experiments for molten TPUs revealed that the temperature at critical gel point, which is defined as the temperature at which the dynamic storage modulus coincides with the loss storage modulus, in the cooling process increased with the progress of aggregation of the hard segments in the TPUs observed in the solid state. The uniaxial elongational viscosity measurements showed that TPUs exhibited an obvious strain hardening behavior with strain rate owing to residual hard segment domains at an operating temperature. It was revealed that the formation of well-organized hard segment domains had a profound effect on the theological properties of TPUs, in particular on their elongational viscosity. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2007.06.006

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/ma0700577

Language：English   Publishing type：Research paper (scientific journal)  

The effects of the dynamic polymerization method and temperature on the molecular aggregation structure and the mechanical and melting properties of thermoplastic polyurethanes (TPUs) were successfully clarified. TPUs were prepared from poly (ethylene adipate) glycol (M-n = 2074), 4,4'-diphenylmethane diisocyanate and 1,4-butanediol by the one-shot (OS) and the prepolymer (PP) methods in bulk at dynamic polymerization temperatures ranging from 140 to 230 degrees C. Glass-transition temperatures (T(g)s) of the soft segment and melting points (T(m)s) of the hard segment domains of OS-TPUs increased and decreased, respectively, with increasing polymerization temperatures, but those of PP-TPUs were almost independent of the polymerization temperature. TO of the soft segment and Tins of the hard segment domains of these TPUs polymerized above 190 degrees C were almost the same regardless of the polymerization method. Solid-state nuclear magnetic resonance spectroscopy (NMR) analyses of OS- and PP-TPUs showed that the relative proton content of fast decay components, which corresponds to the hard segment domains, in these TPUs decreased with increasing polymerization temperatures. These results clearly show that the degree of microphase separation becomes weaker with increasing polymerization temperatures. The temperature dependence of dynamic storage modulus and loss tangent of OS-TPUs coincided with those of PP-TPUs at polymerization temperature above 190 degrees C. The apparent shear viscosity for OS- and PP-TPUs polymerized above 190 degrees C approached a Newtonian behavior at low shear rates regardless of the polymerization method. These results indicate that TPUs polymerized at higher temperatures form almost the same molecular aggregation structures irrespective of the dynamic polymerization method. (c) 2007 Wiley Periodicals, Inc.

DOI： 10.1002/polb.21080

Language：English   Publishing type：Research paper (scientific journal)  

Norbornane diisocyanate (NBDI: 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane) is a new commercialized diisocyanate. NBDI-based polyurethane elastomers (PLJEs) were prepared from poly(oxytetramethylene) glycol (PTMG), NBDI and 1,4-butanediol (BD) by a prepolymer method. Microphase-separated structure and mechanical properties of the NBDI-based PUEs were compared with general aliphatic and cyclo-aliphatic diisocyanate-based PUEs. The diisocyanates used were isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI) and 1,6-hexamethylene diisocyanate (M). Regular polyurethanes were also prepared as hard segment models from each isocyanate and BD to understand the feature of each hard segment chain. The HDI-based PUE showed the largest Young's modulus and tensile strength in the four PUEs due to the ability of crystallization of the hard segment component and the strongest microphase separation. HMDI has both properties of aliphatic and cycloaliphatic diisocyanates because of its high symmetrical chemical structure compared with NBDI and IPDI. On the other hand, the NBDI- and IPDI-based PUEs have an inclination to phase mixing, leading to decreased Young's modulus and tensile strength. The NBDI-based PUE exhibited better thermal properties at high temperatures due to stiff structure of NBDI. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2006.12.057

Language：English   Publishing type：Research paper (scientific journal)  

Biogels and bio-hybrid gels were prepared from myofibril of fish and their properties were evaluated. The muscular protein used was extracted from fish meat. After washing and centrifugal separation, the muscular protein was mixed with 3 wt % of NaCl and the gels were prepared by heating the mixtures from 50 to 90 degrees C. The bio-hybrid gels were prepared from fish protein gel and poly(vinyl alcohol). Tensile tests revealed that the tensile strength, strain at break and Young's modulus of heated hybrid gels prepared at 50, 80 and 90 degrees C increased with increasing preparation temperature. This can be explained by the difference in crosslinking density. Also, the heated gels showed a good response to electric field in acid and alkaline solutions. Young modulus, tensile strength and elongation at break of the bio-hybrid gels increased with an increasing PVA content. Bending of hybrid gels in solutions of various pH under the electric stimulus was observed. The largest bending angle was 20-30 degrees C at pH=1.2.

DOI： 10.1007/s00289-006-0612-5

Language：English   Publishing type：Research paper (scientific journal)  

A diisocyanate baring ether bonds, 1,2-bis(isocyanate)ethoxyethane (TEGDI), was used for the preparation of polyurethane elastomers (PUEs). The PUEs were synthesized with either TEGDI or HDI, poly(oxytetramethylene) glycol (PTMG), and curing agents by a prepolymer method. 1,6-Hexamethylene diisocyanate (HDI) was also used as a control diisocyanate. The TEGDI-based PUEs exhibited highly softened property on account of flexibility of TEGDI itself and weaker phase separation. Another TEGDI-based PUEs were prepared with either poly(oxypropylene) glycol (PPG) or poly (caprolactone) glycol (PCL). Microphase-separated structure of these TEGDI-based PUEs are quite different from those with general diisocyanates and the PUEs were made be greatly softened. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2005.09.009

Language：English   Publishing type：Research paper (scientific journal)  

Surface structure and dynamics in three different polymeric ultrathin systems, such as organosilane monolayers, poly(methyl methacrylate) (PMMA) brushes and poly(amido amine) dendrimer monolayers are discussed. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cis.2004.09.007

Language：English   Publishing type：Research paper (scientific journal)  

Randomly copolymerized poly(carbonate) glycols were employed as starting materials for the synthesis of polyurethane elastomers (PUEs). The poly(carbonate) glycols had hexamethylene (C-6) and tetramethylene (C-4) units between carbonate groups in various composition ratios (C-4/C-6 = 0/100, 50/50, 70/30, and 90/10), and the number-average molecular weights of these poly(carbonate) glycols were 1000 and 2000. The PUEs were synthesized with these poly(carbonate) glycols, 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol by a prepolymer method. Differential scanning calorimetry measurements revealed that the difference between the glass-transition temperature of the soft segment in the PUEs and the glass-transition temperature of the original glycol polymer decreased and the melting point of the hard-segment domain increased with an increasing C-4 composition ratio. The microphase separation of the poly(carbonate) glycol-based PUEs likely became stronger with an increasing C-4 composition ratio. Young's modulus of these PUEs increased with an increasing C-4 composition ratio. This was due to increases in the degree of microphase separation and stiffness of the soft segment with an increase in the C-4 composition ratio. The molecular weight of poly(carbonate) glycol also influenced the microphase-separated structure and mechanical properties of the PUEs. The addition of different methylene chain units to poly(carbonate) glycol was quite effective in controlling the microphase-separated structure and mechanical properties of the PUEs. (C) 2004 Wiley Periodicals, Inc.

DOI： 10.1002/polb.20303

Language：English   Publishing type：Research paper (scientific journal)  

Effect of side methyl and dimethyl groups of soft segment component on polyurethane elastomers (PUEs) was investigated with and without elongation. The polymer glycols used were poly(oxytetramethylene) glycol (PTMG), PTMG with dimethyl groups (PTG-X) and methyl groups (PTG-L). Phase separation of the PUEs became weaker with an increasing methyl group content. Tensile test revealed that the increasing methyl group concentration made the PUEs be soften and weaken. The PTMG based PUEs obviously exhibited elongation-induced crystallization during elongation process. In contrast, for the PTG-L and PTG-X based PUEs, crystallinity decreased with an increasing side methyl group content, and the PUEs with PTG-L and PTG-X with highest methyl group content did not crystallize. We succeeded the control of the crystallization behavior of elastomers under an elongation by the introduction of side methyl groups. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2004.09.061

Language：English   Publishing type：Research paper (scientific journal)  

A novel diisocyanate, 1,2-bis(isocyanate)ethoxyethane (TEGDI), whose backbone is ether bonds was used for the preparation of polyurethane elastomers (PUEs). 1,6-Hexamethylene diisocyanate (HDI) was also used as a control. The PUEs were prepared with either TEGDI or HDI, poly(oxytetramethylene) glycol (PTMG), and curing agent by a prepolymer method. Differential scanning calorimetry, infrared spectroscopy, and wide-angle X-ray diffraction revealed that the phase separation of the network TEGDI-based PUEs was much weaker compared with that of the HDI ones. Highly softened TEGDI-based PUEs were successfully prepared on account of flexibility of TEGDI itself and weaker phase separation.

DOI： 10.1021/ma0359988

Language：English   Publishing type：Research paper (scientific journal)  

Thermal transitions and morphological changes in Cloisite organoclays were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and in situ simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) over the temperature range of 30-260 degreesC. On the basis of DSC and FTIR results, the surfactant component in organoclays was found to undergo a melting-like order-disorder transition between 35 and 50 degreesC. The transition temperatures of the DSC peaks (T-tr) in the organoclays varied slightly with the surfactant content; however, they were significantly lower than the melting temperature of the free surfactant (dimethyldihydrotallowammonium chloride; T-m = 70 degreesC). FTIR results indicated that within the vicinity of Ttr, the gauche content increased significantly in the conformation of surfactant molecules, while WAXD results did not show any change in three-dimensional ordering. Multiple scattering peaks were observed in SAXS profiles. In the SAXS data acquired below T-tr, the second scattering peak was found to occur at an angle lower than twice that of the first peak position (i.e., nonequidistant scattering maxima). In the data acquired above Ttr, the second peak was found to shift toward the equidistant position (the most drastic shift was seen in the system with the highest surfactant content). Using a novel SAXS modeling technique, we suggest that the appearance of nonequidistant SAXS maxima could result from a bimodal layer thickness distribution of the organic layers in organoclays. The occurrence of the equidistant scattering profile above T-tr could be explained by the conversion of the bimodal distribution to the unimodal distribution, indicating a redistribution of the surfactant that is nonbounded to the clay surface. At temperatures above 190 degreesC, the scattering maxima gradually broadened and became nonequidistant again but having the second peak shifted toward a scattering angle higher than twice the first peak position. The changes in SAXS patterns above 190 degreesC could be attributed to the collapse of organic layers due to desorption and/or degradation of surfactant component, which was supported by the TGA data.

DOI： 10.1021/la035361h

Language：English   Publishing type：Research paper (scientific journal)  

Functionally graded polyurethane elastomers (FGPUEs) were prepared with two molds fixed at different temperatures (30 and 150degreesC). The effects of the molar ratio of the curing agent (60/40, 75/25, or 97/3 1,4-butane diol/1,1,1-trimethylol propane) and the molecular weight of the polymer glycol (number-average molecular weight = 2000 or 3000) on the molecular aggregation state and mechanical properties of the FGPUEs were investigated with differential scanning calorimetry, polarized optical microscopy, dynamic viscoelastic measurements, and tensile tests. The aggregation state of the FGPUEs was changed continuously from the one side (lower temperature side) to the other side (higher temperature side); for example, the glass-transition temperature gradually increased in this direction. Also, the number of spherulites formed in the FGPUEs increased in the same manner. In the mechanical tests, the tensile strength and elongation at break of the lower temperature side were higher than those of the higher temperature side. This was correlated with the strong phase separation of the lower temperature side. The poly(oxytetramethylene glycol)based FGPUE with a chain extender of 75 wt % showed the largest degree of the temperature gradient. (C) 2003 Wiley Periodicals, Inc.

DOI： 10.1002/polb.10628

Language：English   Publishing type：Research paper (scientific journal)  

Dielectric measurement in the range 0.1 Hz to 1 MHz were used to study the motions of polymers and ions in an ion-conducting polymer, polypropylene oxide containing small quantities (on the order of 1%) of lithium ions (LiClO4), confined as a sandwich of uniform thickness between parallel insulating mica surfaces. In the dielectric loss spectrum, we observed three peaks; they originated from the normal mode of the polymer, segmental mode of the polymer, and ion motions. With decreasing film thickness, the peak frequencies corresponding to the normal mode and ion motion shifted to lower frequencies, indicating retardation due to confinement above 30 nm. This was accompanied by diminished intensity of the dielectric normal-mode relaxation, suggesting that confinement diminished the fluctuations of the end-to-end vector of the chain dipole in the direction between the confining surfaces. On the contrary, the segmental mode was not affected at that thickness. Finally, significant retardation of the segmental mode was observed only for the thinnest film (14 nm). The different dynamical modes of the polymer (segmental and slowest normal modes) respond with different thickness and temperature dependence to confinement.

DOI： 10.1140/epje/i2001-10090-x

Language：English   Publishing type：Research paper (scientific journal)  

Nanotribological behaviors of organosilane monolayers prepared by the Langmuir-Blodgett (LB) and chemisorption methods are discussed in terms of their aggregation states. Aggregation structure of the LB n-octadecyltrichlorosilane (OTS-C18) monolayers changed from a rectangular to an amorphous phase via a hexagonal phase with increasing temperature. A distinct lateral force decrease accompanies the phase transition. The LB alkyltrichlorosilane monolayers with longer alkyl chains were in a crystalline state at 293 K. The lateral force of the LB alkyltrichlorosilane monolayers at 293 K increased with increasing chain length. The n-triacontyltrichlorosilane LB monolayer (TATS-C30) in a rectangular phase showed higher lateral force than that of the alkyltrichlorosilane with shorter alkyl chains in a hexagonal phase. The lateral force of the OTS-C18 monolayer prepared by the LB method was higher than that of the chemisorbed one because of the higher packing density of alkyl chain for the LB monolayer, though both monolayers are in a hexagonal phase at 293 K. A large increase in lateral force was observed for the 18-nonadecenyltrichlorosilane (NTS) after oxidation of vinyl end groups. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0304-3991(02)00100-6

Language：English   Publishing type：Research paper (scientific journal)  

The n-octadecyltrichlorosilane (OTS, CH3(CH2)(17)SiCl3), 18-nonadecenyltrichlorosilane (NTS, CH2=CH(CH2)(17)- SiCl3), [2-(perfluorooctyl)ethyl]trichlorosilane (FOETS, CF3(CF2)(7)CH2CH2SiCl3) monolayers, and their mixed monolayers were used as model surfaces for the study of protein adsorption mechanism. Surface plasmon resonance (SPR) spectroscopy was applied to analyze the protein adsorption behavior onto the monolayer surfaces. The surfaces after exposure of these monolayers to bovine serum albumin (BSA) and gamma-globulin(IgG) solutions were observed with atomic force microscope(AFM). AFM observation revealed that the charged protein either below or above pI was preferentially adsorbed onto the FOETS phase of the phase-separated (OTS/FOETS) mixed monolayer. in situ AFM observation of monolayer surfaces in BSA solution also revealed the preferential adsorption of BSA onto the hydrophobic FOETS surface. SPR clarified that the amount of adsorbed protein in the charged state was lower than that in the neutral state. Adhesion force was not detected in the force-distance curve measurement between negatively-charged HOOC(CH2)(9)SH chemisorbed cantilever tip and the OTS phase in the presence of adsorbed BSA on FOETS phase of mixed monolayer. These results indicate that the preferential adsorption of protein onto the FOETS phase for the mixed monolayer systems at either below or above pI is due to, (1) the minimization of interfacial free energy between the monolayer surface and the buffer solution; and (2) the electrostatic repulsion among protein molecules bearing charges. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7765(01)00231-4

Language：English   Publishing type：Research paper (scientific journal)  

A novel and convenient method to prepare organosilane monolayers was proposed. Pure water was put onto a cleaned silicon wafer and then a toluene solution of n-trichloro(octadecyl)silane (OTS) was spread on it. X-ray photoelectron spectroscopy and atomic force microscopic observation revealed that an OTS monolayer was successfully formed on the solid substrate after the water was evaporated. The static water contact angle of the silicon wafer covered with the OTS monolayer was 105 degrees. Molecular aggregation states of the OTS monolayer were examined by electron diffraction, Fourier transform infrared spectroscopic. X-ray reflectivity, and grazing incidence X-ray diffraction measurements. The prepared OTS monolayer was in a two-dimensional hexagonal crystalline state at 293 K and alkyl chains of the OTS molecules were oriented normal to the surface. Also, the alkyl chains in the monolayer were highly ordered, although the experimental procedure for the monolayer preparation was quite simple. The development of this novel method to prepare a low energy surface will contribute to the material science as well as having industrial applications.

DOI： 10.1246/bcsj.74.1397

Language：English   Publishing type：Research paper (scientific journal)  

Crystal transition behavior of lignoceric acid (LA) monolayer was structurally investigated by electron diffraction (ED) in conjunction with scanning force microscopy (SFM). LA molecules form two-dimensional hexagonal crystallites right after one spreads a solution at the air/water interface. The hexagonal-rectangular transition of the LA monolayer was attained by two different experimental procedures: monolayer compression under an isothermal condition and monolayer cooling under an isobaric condition. In the compression process, the hexagonal and rectangular phases coexisted in the monolayer at the surface pressure, pi, of 10 mN m(-1), which was slightly lower than the plateau pressure, and the subphase temperature of 293 K. When the pi exceeded the plateau pressure, the hexagonal phase in the LA monolayer was entirely transformed to the rectangular one. High-resolution SFM showed that the crystal transition from the hexagonal to rectangular phase proceeded via a quasi-disordered phase upon compression. A similar hexagonal-rectangular transition was also observed during the monolayer cooling process at the pi of 15 mN m(-1). Based on SFM observation, we claimed that the molecular ordering or packing state in the rectangular lattice induced by cooling was better than that by the monolayer compression. Finally, the crystal transition mechanisms for these two procedures were proposed.

DOI： 10.1246/bcsj.74.765

Language：English   Publishing type：Research paper (scientific journal)  

The n-octadecyltrichlorosilane (OTS, CH3(CH2)(17)SiCl3), 18-nonadecenyltrichlorosilane (NTS, CH2=CH(CH2)(17)SiCl3), [2-(perfluorooctyl)ethyl] trichlorosilane (FOETS, CF3(CF2)(7)CH2CH2SiCl3) monolayers, and their mixed monolayers were used as the model substrates for the study of protein adsorption mechanism. Surface plasmon resonance (SPR) spectroscopy was applied to analyze the protein adsorption behavior onto the surface of the monolayers. Atomic force microscope (AFM) was used to observe the monolayer surfaces after exposure of these monolayers to bovine serum albumin (BSA) and gamma -globulin(IgG) solution. AFM observation revealed that the charged protein either below or above the isoelectric point was preferentially adsorbed onto the FOETS phase of the (OTS/FOETS) mixed monolayer. SPR revealed that the amount of adsorbed protein in the charged state was lower than that in the neutral state. These results indicate that the preferential adsorption of protein onto the FOETS phase for the mixed monolayer systems at either below or above pi is due to (1) the minimization of interfacial free energy between the monolayer surface and the buffer solution, and (2) the electrostatic repulsion among protein molecules bearing charges.

DOI： 10.1002/1521-3900(200103)167:1<271::AID-MASY271>3.0.CO;2-Y

Language：English   Publishing type：Research paper (scientific journal)  

Relationships between the molecular aggregation state and the molecular motion of organosilane monolayers with various chain lengths prepared by the Langmuir-Blodgett (LB) method were investigated by lateral force microscopic, Fourier transform-infrared (FT-IR) spectroscopic, and electron diffraction (ED) measurements. The lateral force of the organosilane monolayers increased with increasing their chain length. This is mainly because the intermolecular cohesive energy is proportional to the number of carbons in a chain. The lateral force of the alkylsilane monolayer was compared with that of the fluoroalkylsilane monolayer for the corresponding alkyl chain length. Consequently, the fluoroalkylsilane monolayer showed higher lateral force than the alkylsilane one. Temperature-dependent ED and FT-IR measurements revealed that the molecular aggregation state of the n-octadecyltrichlorosilane (OTS) monolayer changed from the rectangular lattice to the amorphous state via the hexagonal lattice with increasing temperature. The transition temperatures, rectangular to hexagonal and hexagonal to amorphous, were found to be 240 and 333 K, respectively. The distinct lateral force decrease was concurrently observed for the OTS monolayer at 240 and 333 K. The remarkable decrement of the lateral force at 240 K might be attributed to the decreasing molecular density and the activation of molecular motion (rotational motion along the molecular axis) owing to the rectangular-hexagonal crystal transition. And, the second remarkable depression of the lateral force observed at 333 K might come from the activation of thermal molecular motion due to the melting of alkyl chains.

DOI： 10.1021/la0004303

Language：English   Publishing type：Research paper (scientific journal)  

The n-octadecyltrichlorosilane (OTS) monolayer was prepared by the Langmuir-Blodgett method. The formation mechanism of the OTS monolayer on the water subphase was investigated on the basis of electron diffraction (ED) study, Fourier transform infrared external reflection spectroscopic (FT-IR/ERS) measurement and high-resolution atomic force microscopic (AFM) observation. Morphological changes in the monolayer in a compression process were observed by AFM. FT-IR/ERS measurement was performed for the monolayer at the air/water interface, and that the ED and AFM observations were done for the monolayer transferred onto substrate. ED study and high-resolution AFM observation revealed that the OTS monolayer was in a crystalline state at 293 K. Also, FT-IR/ERS measurement and AFM observation showed that the OTS molecules crystallize and polymerize spontaneously right after spreading a toluene solution of OTS on the water subphase. Then, during a monolayer compression, the crystalline OTS monolayer domain did not form the larger ones by sintering at the crystalline domain interface at 293 K. Also, AFM and ED observations revealed that the defect-diminished OTS monolayer could be successfully prepared by using the multi-step creep method. (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0927-7757(00)00444-1

Language：English   Publishing type：Research paper (scientific journal)  

A comparative study in molecular arrangements of the n-octadecyltrichlorosilane (OTS) monolayer prepared by the Langmuir method and the chemisorption methods were carried out on the basis of grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XR) measurements. The OTS molecules in the Langmuir OTS monolayer uniformly tilt ca. 8-10 degrees to the surface normal and packed in a hexagonal lattice with the (10) spacing of 0.412 nm. On the other hand, the OTS molecules in the chemisorbed OTS monolayer tilt ca. 15-17 degrees to the surface normal and also crystallite orient randomly in the two-dimensional plane. The average magnitude of the (10) spacing of the chemisorbed OTS monolayer was ca, 0.417 nm. Direct evidence that the packing density of the Langmuir OTS monolayer was higher than that of the chemisorbed OTS monolayer was obtained by GIXD and XR measurements for the first time.

DOI： 10.1021/la9909042

Language：English  

Molecular arrangement of polymerized n-octadecyltrichlorosilane (OTS, CH3(CH2)(17)SiCL3) monolayer transferred onto hydrophilic substrate by an upward drawing method was investigated with a transmission electron microscope (TEM) and an atomic force microscope(AFM). The electron diffraction (ED) pattern of the OTS monolayer revealed that the OTS molecules were regularly arranged in a hexagonal array with a (10) spacing of ca. 0.42 nm. The high-resolution AFM image of the OTS monolayer in a scan area of 10 x 10 nm(2) exhibited the individual methyl group of which packing was a hexagonal array in a similar molecular arrangement concluded on the basis of the ED study. Also, the point defect in the crystalline OTS monolayer was successfully observed for the first time.

DOI： 10.1021/la970040p

Language：English   Publishing type：Research paper (scientific journal)  

Alkyltrichlorosilanes, [2-(perfluorooctyl)ethyl]tri chi oro silane (FOETS) and their mi red monolayers were polymerized on the water subphase and were subsequently immobilized onto the silicon wafer surface by covalent bonding. Atomic force microscopic (AFM) observation of the [n-octadecyltrichlorosilane(OTS)/FOETS] mixed monolayer revealed that the crystalline OTS formed circular domains of similar to 1-2 mu m in diameter that were surrounded by an amorphous FOETS matrix. Lateral force microscopic (LFM) and scanning viscoelasticity microscopic (SVM) observations of the (OTS/FOETS) mixed monolayer could also distinguish the difference in the physical and mechanical properties between domain and matrix. The (alkylsilane/FOETS) mixed monolayers with a shorter alkyl chain such as n-dodecyltrichlorosilane (DDTS) did not show the phase-separated structure maybe due to the lack in crystallinity of DDTS component. AFM observation of the [crystalline fatty acid (nonreactive)/FOETS (reactive)] mixed monolayer also revealed the phase-separated structure. The crystalline fatty acid domains in the mixed monolayer were extracted by solvent and then, the monolayer of FOETS with the holes of similar to 1-2 mu m in diameter, that is, the (Si/FOETS) monolayer was finally obtained. The Si phase of (Si/FOETS) was backfilled with the another organosilane by chemisorption. Then, the [(3-mercaptopropyl) trimethoxysilane (MTS)/FOETS] mixed monolayer was newly obtained by the chemisorption of MTS. The absorption of bovine serum albumin (BSA) onto mixed monolayers was studied by exposure of the mixed monolayers to a BSA solution. BSA was preferentially adsorbed onto the MTS part due to a specific reaction between disulfide bond (-S-S-) in BSA and SH groups in MTS. On the other hand, in the case of (OTS/FOETS) mixed monolayer, BSA adsorbed preferentially onto the FOETS matrix in order to minimize the interfacial free energy in the aqueous environment. (C) 1996 American Vacuum Society.

DOI： 10.1116/1.580331

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Responsible for pages：第7章   Language：Japanese  

Responsible for pages：第5章, pp.75-98   Language：Japanese  

Responsible for pages：157-163   Language：Japanese  

Responsible for pages：278-279   Language：Japanese  

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Xian, China   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鳥取   Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.6

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Cheju, Korea   Country：Japan  

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Venue：ちよだプラットフォームスクウェア   Country：Japan  

Event date： 2019.1 - 2019.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Tokyo Tech Front, Royal Blue Hall,Tokyo Institute of Technology   Country：Japan  

Event date： 2017.3

Language：English   Presentation type：Oral presentation (general)  

Venue：Shenzhen, China   Country：China  

Event date： 2016.11 - 2015.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：タワーホール船堀   Country：Japan  

Event date： 2015.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Chateraise Gateaux Kingdom Sapppro, Japan   Country：Japan  

Event date： 2015.9

Presentation type：Oral presentation (general)  

Venue：Hokkaido University, Japan   Country：Japan  

Event date： 2015.3

Presentation type：Oral presentation (general)  

Venue：千葉   Country：Japan  

Event date： 2015.3

Presentation type：Oral presentation (general)  

Venue：千葉   Country：Japan  

Event date： 2015.3

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2015.1

Presentation type：Oral presentation (general)  

Venue：滋賀   Country：Japan  

Event date： 2014.12

Presentation type：Oral presentation (general)  

Venue：仙台   Country：Japan  

Event date： 2014.12

Presentation type：Oral presentation (general)  

Venue：名古屋   Country：Japan  

Event date： 2014.12

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2014.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：つくば国際会議場   Country：Japan  

Event date： 2014.12

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2014.11

Presentation type：Oral presentation (general)  

Venue：久留米   Country：Japan  

Event date： 2014.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟   Country：Japan  

Event date： 2014.11

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2014.10 - 2013.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Chengdu   Country：China  

Event date： 2014.10

Presentation type：Oral presentation (general)  

Venue：福井   Country：Japan  

Event date： 2014.9 - 2014.10

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2014.9

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Event date： 2014.9

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Event date： 2014.9

Presentation type：Oral presentation (general)  

Venue：博多   Country：Japan  

Event date： 2014.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2014.5

Presentation type：Oral presentation (general)  

Venue：名古屋   Country：Japan  

Event date： 2014.5

Presentation type：Oral presentation (general)  

Venue：名古屋   Country：Japan  

Event date： 2014.5

Presentation type：Oral presentation (general)  

Venue：埼玉   Country：Japan  

Event date： 2014.5

Presentation type：Oral presentation (general)  

Venue：埼玉   Country：Japan  

Event date： 2014.5

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2013.9

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2012.9

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岐阜   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：韓国   Country：Korea, Republic of  

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：韓国   Country：Korea, Republic of  

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：大阪   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：埼玉   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：滋賀   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：岡山   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：神奈川   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：千葉   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：大阪   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：English  

We successfully achieved inclusion of fullerene (C₆₀) into the grafted-poly(MMA-NMA) chains in THF without inducing the formation of C₆₀ clusters and/or aggregation between the polymer-grafted silica particles. Polymer grafting onto silica was conducted by reacting 12nm colloidal silica particles with polymeric silane, prepared by radical polymerization, in THF without particle aggregation. Molecules of C₆₀ were effectively included into grafted polymer chains in the THF suspension of the poly(MMA-NMA)-grafted silica, prepared from polymers with molecular weights of 33 200 and 48 000, without the formation of C₆₀ clusters and without aggregation between the silica composite particles. It was observed that the maximum C₆₀inclusion into poly(MMA-NMA) chains grafted on 11.2 mg silica particles was 0.25 mg, corresponding to 2.7 C₆₀ molecules per unit SiO₂ particle.

DOI： 10.1038/pj.2014.24

Language：English  

The relationship between a microphase-separated structure and dynamic viscoelastic properties of polyurethane elastomers (PUEs) prepared at various temperatures and cross-linking agent contents were investigated. The PUEs were synthesized with poly(oxytetramethylene) glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) and a mixture of BD and 1,1,1-trimethylol propane (TMP) by a prepolymer method. The PUEs are in the strong-segregation limit. The microphase-separated structure was investigated using Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS) and atomic force microscope (AFM). The extent of microphase separation of the PUEs became stronger and weaker with increases in curing temperature and trifunctional TMP content, respectively. The consistent results obtained in this study would be quite helpful to design the desirable PUEs.

DOI： 10.1678/rheology.42.143

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：English  

Spherulite size graded polyurethane elastomers (PUEs) were prepared using a mold with a temperature gradient from different polymer glycols, 4,40-diphenylmethane diisocyanate (MDI) and a mixture of 1,4-butanediol (BD), and 1,1,1-trimethylol propane (TMP) as a curing agent by a prepolymer method. The used polymer glyocols were poly(oxytetramethylene)glycol (PTMG, M _n = 2000), poly(ethylene adipate)glycol (PEA, M_n = 2000), and poly(hexamethylene adipate)glycol (PHA, M_n = 2000). The effect of polyether and polyester glycols and the temperature gradient on the micro-aggregation structure and mechanical properties were studied by polarized optical microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, micro-hardness test, pulsed nuclear magnetic resonance spectroscopy, and tensile test. The prepared PUEs had spherulite size graded super-structure. Spherulite sizes of the PUEs depended significantly on the temperature gradient of the mold. Spherulite of the PUEs in contact with the mold at low temperature was significantly smaller and more dense than that contacting the mold at high temperature. The spherulite diameter of PTMG-, PEA-, and PHA-PUEs changed from 12.6 to 16.3 m̈m, 8.4 to 15.6 m̈m, and 10.4 to 16.0 m̈m, respectively from the lower temperature side (LTS) toward the higher temperature side. In contrast, the number of spherulites became sparser toward the higher one. The glass transition temperature (T_g) of PTMG-, PEA-, and PHA-based PUEs elevated from -55.3°C, -19.0°C and -33.8°C at the LTS to -48.6°C, -17.8°C and -32.8°C at the HTS, respectively. T_g of all PUEs exhibited elevation from the LTS toward the higher one. This result associated with the strong microphase separation of the LTS.

DOI： 10.1002/app.30047

Language：English  

Polycarbonate based thermoplastic polyurethanes (CPU2) were prepared and coated onto polyamide 6 (PA 6) fibers. The CPU2 thin film coatings were prepared by dipping the PA 6 fibers into a viscous CPU2 adduct and cured at 100 °C for 12 h. Both the tensile strength and the elongation at break of the CPU2 thin film coated PA 6 fibers (CPU2-PA6) increased although both the magnitudes of CPU2 are much lower than for the original PA 6 fibers. FE-SEM observation revealed that ; there existed an interface interaction region of 10 um at the interface of PA 6 fiber and the CPU2 thin film coating. Generally , speaking, it is considered that the break of PA 6 fibers is due to the formation of the micro-cracks on the fiber surface when it is under a tensile load. The coating of CPU2 onto the PA 6 fibers reduced the formation of micro-cracks during the elongation process, resulted in the improvement of the mechanical properties. Also, the CPU2-PA6 fibers when exposed to weathering i• tests to check the weathering resistance, showed an increase in the tensile strength for 0-50 h of exposure. This was due to the ; UV light induced crystalline transformation, i.e., from the a crystalline phase to the y crystalline phase. The CPU2-PA6 fibers j I almost retained the strength even after 200 h of exposure in a weatherometer. The crystalline transformations due to the UV 't irradiations have not been reported yet. Also, the CPU2 showed good adhesion property with the PA 6 films. The blending i with various polymers or composites is generally employed for the performance enhancement of PA 6 fibers. On the contrary, the method employed in this study improved the performance of PA 6 fibers without changing its inherent morphological properties.

DOI： 10.1295/polymj.PJ2008286

Language：English  

Highly hydrophilic polyurethane elastomers (PUEs) were synthesized from 1,2-bis(isocyanate) ethoxyethane (TEGDI), poly(ethylene oxide-co-propylene oxide) copolyol (EOPO) and 1,4-butane diol/1,1,1-trimethylol propane (75/25) (wt/wt) by a prepolymer method. 4,4′-Diphenylmethane diisocyanate (MDI)-based PUEs were synthesized as a control as well. Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) measurements revealed that the degree of microphase separation of the TEGDI-based PUEs was much weaker than for the MDI-based PUEs. Young's modulus and elongation at break of the TEGDI-based PUEs were quite lower and larger than for the MDI-based PUEs, respectively. This is due to quite weak cohesion force of the hard segment chains in the TEGDI-based PUEs. The degree of swelling of the TEGDI-based PUEs was five times larger than for the MDI-based one. This is associated with the hydrophilic nature of TEGDI and weak cohesion force in the TEGDI-based PUEs.

DOI： 10.1016/j.polymer.2009.05.030

Language：English  

The microphase-separated structure of polyurethane bulk and thin films were investigated using atomic force microscopy (AFM). The polyurethane (PUs) were synthesized with poly(oxytetramethylene) glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) by a prepolymer method. The hard segment contents were 34 and 45wt%. Polarized optical microscopy (POM) revealed that the 34wt% PUE is homogeneous at a macroscopic level, while the 45wt% one is macrophase-separated into two phases. One phase forms spherulites of ca. 2-5 urn in diameter. AFM observation for the 34 wt % PUE showed the microphase-separated structure, consisting of hard segment domains and a soft segment matrix. In contrast, for the 45 wt % PUE, a lot of the hard segment domains were observed in the spherulite region, indicating that spherulites include much amount of hard segment component, in contrast, outside of spherulite exhibited similar structure to that of 34 wt % one. For the PU bulk, the different microphase-separated structure in the inside and outside of spherulite was successfully observed for the first time. Also, the microphase-separated structure of PU films was investigated as a function of the film thickness. The PU films exhibited similar microphase-separated structure. For the thicker film (-200nm), the interdomain spacing almost corresponded to bulk one. On the other hand, that for the film thickness below 7nm dramatically decreased. This seems to be simply related to a decreasing space. We obtained the experimental data, which the phase-separated domain size of multiblock copolymer decreased with decreasing film thickness.

DOI： 10.1295/polymj.PJ2008186

Language：English  

Measurements are presented how chain and microphase-separated structures of ultrathin polyurethane (PU) films are controlled by the thickness. The film thickness is varied by a solution concentration for spin coating. The systems are PUs prepared from commercial raw materials. Fourier-transform infrared spectroscopic measurement revealed that the degree of hydrogen bonding among hard segment chains decreased and increased with decreasing film thickness for strong and weak microphase separation systems, respectively. The microphase-separated structure, which is formed from hard segment domains and a surrounding soft segment matrix, were observed by atomic force microscopy. The size of hard segment domains decreased with decreasing film thickness, and possibility of specific orientation of the hard segment chains was exhibited for both systems. These results are due to decreasing space for the formation of the microphase-separated structure.

DOI： 10.1088/1742-6596/184/1/012028

Language：English  

Thermoplastic polyurethane (TPU) was thin film coated on polyamide 6 (PA6) fibers by the reactive bulk and solution coating techniques. The thickness of the coating was 40 um for the reactive bulk coating technique and 20 μm for the solution coating. The increase in crystallinity, the formation of the interface interaction region and the entry of TPU thin film coating into the micro-cracks under tensile stress resulted in the increase of strength as well as elongation of the TPU coated PA6 fibers. The microphase separated-structure and the orientation of the hard segment domains of the TPU thin film coating on the PA6 fiber surface had an impact on the force alignment of the PA6 fiber when under a mechanical stress. The hard segment domains of the TPU thin film which was prepared by a solution coating technique showed better alignment to the deformation force direction compared to the reactive bulk based one. This led to better mechanical strength of the former based TPU coated PA6 fiber. The TPU is a son material and the improvement of mechanical property with same should be specially noted. So an understanding of both type of coating techniques is very useful in various industrial applications of PA6 fibers.

DOI： 10.2115/fiber.65.236

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

DOI： https://doi.org/10.1678/rheology.36.229

Language：English  

A novel diisocyanate, 1,2-bisisocyanate ethoxyethane (TEGDI) whose backbone is ether bonds, was used for the preparation of polyurethane elastomers (PUEs). Highly softened TEGDI-based PUEs were successfully prepared on account of flexibility of TEGDI itself and weaker phase separation. A relationship between conformation and molecular mobility of the soft segment were investigated using dynamic viscoelastic measurement. The peaks of α relaxation of the soft segment chains were clearly observed in the loss tangent (tan δ) curves at various strains. The onset temperature of α relaxation decreased with increasing strain. This result indicates that the size of cooperative motion of the glass transition decreased due to the orientation of the soft segment chains with increasing strain. The effect of the microaggregation structure on the rheological properties of thermoplastic polyurethane (TPU) were investigated. The TPUs showed the strain hardening of uniaxial elongation viscosity with increasing annealing temperature owing to residual hard segment domains at an operating temperature. It was revealed that the formation of well-organized hard segment domains had a profound effect on the rheological properties of TPUs, in particular on their elongational viscosity.

DOI： 10.1678/rheology.36.229

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：English  

The effect of side methyl and dimethyl groups of the soft segment component on the microphase-separated structure and mechanical properties of Polyurethane elastomers (PUEs) was investigated. Poly(oxytetramethylene) glycol (PTMG), and PTMG incorporating dimethyl groups (PTG-X) and methyl side groups (PTG-L) were used as a polymer glycol, which forms a soft segment in the PUEs. The PUEs were synthesized with 4,4′-dipheylmethane diisocyanate [1, 1′- methylenebis(4-isocyanatobenzene)], 1,4-butane diol, and 1,1,1-trimethylol propane by a prepolymer method. The degree of microphase separation of the PUEs became weaker with increasing side group content in polymer glycols. Dynamic viscoelastic properties measurement showed reorganized-crystallization and melting of the soft segment for the PUEs based on PTMG, PTG-L, and PTG-X with a lower content of the side groups, but not for a PTG-L and PTG-X with higher content of the side groups. Tensile testing revealed that increasing methyl group concentration made the PUEs soften and weaken. The PTMG-based PUEs obviously exhibited strain-induced crystallization of the soft segment chains during elongation process. In contrast, for the PTG-L and PTG-X-based PUEs, crystallinity decreased with increasing side group content, and the PUEs with PTG-L and PTG-X with highest methyl group content did not crystallize even at a large strain.

DOI： 10.1002/polb.21540

Language：English  

Polyurethane elastomers (PUEs) were synthesized with poly(oxytetramethylene) glycol (PTMC), 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD)/1,1,1-trimethylol propane (TMP) by a prepolymer method. The degree of microphase separation of bulk and ultrathin films for these PUEs was confirmed by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and atomic force microscopy (AFM). In the bulk films, FT-IR and DSC measurements revealed that the degree of micro-phase separation strengthened with increasing BD content. AFM observation of the BD-PUE showed hard segment domains surrounded by a soft segment matrix. The domains ranged in size from 10-20 nm, while BD/TMP- and TMP PUEs did not have clear domains. On the other hand, AFM observation was carried out on thin films (200 mm in thickness) and ultrathin films (approximately 8-5 nm) prepared by spin-coating the different concentrations of PUE solutions. The microphase separated strucuture under 10 nm in thickness showed marked decreases in the size of the microphase-separated domain.

DOI： 10.1002/masy.200850702

Language：English  

I investigated the specific chain structure of polyurethane (PU) films, which possess strong polar groups in the main chains and multiblock structure under confinement. The PU was synthesized from poly (oxytetramethylene) glycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) by a prepolymer method. The hard segment contents were 20, 34 and 45 wt%. The ultrathin PU films were prepared onto a silicon wafer from a PU tetrahydrofuran solution by spin coating. The PU films exhibited microphase-separated structures, which are composed of hard segment domains surrounded by a soft segment matrix. For thicker films (∼200 nm), interdomain spacing almost corresponded to bulk value. On the other hand, it dramatically decreased for film thickness below 7 nm. This effect seems to be directly related to the decreasing film thickness. This is the first report, in which the phase-separated domain size of multiblock copolymers decrease with decreasing film thickness.

DOI： 10.1295/koron.64.498

Language：English  

The effects of the molecular aggregation structure on the rheological properties of thermoplastic polyurethane (TPU) were investigated. The TPU was composed of poly{(tetramethylene adipate)-co-(hexamethylene adipate)} glycol as the soft segments, 4,4′-diphenylmethane diisocyanate and 1,4-butanediol as the hard segments. The TPU sheets prepared by injection molding were annealed at various temperatures from 23 to 120 °C to vary the molecular aggregation structure. Glass transition temperature of the soft segment and melting points of the hard segment domains of the TPUs decreased and increased, respectively, with increasing annealing temperature. The results of DSC, solid-state NMR spectroscopy and dynamic viscoelastic measurements revealed that the degree of micro-phase separation of the TPUs becomes stronger with increasing annealing temperature due to the progress of formation of well-organized hard segment domains. The dynamic temperature sweep experiments for molten TPUs revealed that the temperature at critical gel point, which is defined as the temperature at which the dynamic storage modulus coincides with the loss storage modulus, in the cooling process increased with the progress of aggregation of the hard segments in the TPUs observed in the solid state. The uniaxial elongational viscosity measurements showed that TPUs exhibited an obvious strain hardening behavior with strain rate owing to residual hard segment domains at an operating temperature. It was revealed that the formation of well-organized hard segment domains had a profound effect on the rheological properties of TPUs, in particular on their elongational viscosity.

DOI： 10.1016/j.polymer.2007.06.006

Language：English  

The role of film thickness and interfacial interaction for controlling the size of microphase separation is described. XPS measurement was carried out to analyze the surface chemical composition of the PU films. The interdomain spacing of microphase-seaparated structure in the PU films were investigated by grazing incident small-angle X-ray scattering (GISAXS) measurement. As the film thickness decreases, the space for the crystallization of the hard segment chains become smaller. With decreasing film thickness, the size of the microphase-separated domains decrease, resulting in the amount of the interfacial region between hard segment domains and soft segment matrix increases. Fourier-transform infrared (FT-IR) spectra shows that the aggregation of the hard segment chains become weaker with decreasing film thickness. Strong polarity of the urethane groups leads to the strong interaction between the PU films and substrate surface, which results in the formation of the microphase-separated domain size.

DOI： 10.1021/ma0700577

Language：English  

The effects of the dynamic polymerization method and temperature on the molecular aggregation structure and the mechanical and melting properties of thermo-plastic polyurethanes (TPUs) were successfully clarified. TPUs were prepared from poly (ethylene adipate) glycol (M_n = 2074), 4,4′-diphenylmethane diisocyanate and 1,4-butanediol by the one-shot (OS) and the prepolymer (PP) methods in bulk at dynamic polymerization temperatures ranging from 140 to 230°C. Glass-transition temperatures (T_gs) of the soft segment and melting points (T_ms) of the hard segment domains of OS-TPUs increased and decreased, respectively, with increasing polymerization temperatures, but those of PP-TPUs were almost independent of the polymerization temperature. T_gs of the soft segment and T _ms of the hard segment domains of these TPUs polymerized above 190°C were almost the same regardless of the polymerization method. Solid-state nuclear magnetic resonance spectroscopy (NMR) analyses of OS-and PP-TPUs showed that the relative proton content of fast decay components, which corresponds to the hard segment domains, in these TPUs decreased with increasing polymerization temperatures. These results clearly show that the degree of microphase separation becomes weaker with increasing polymerization temperatures. The temperature dependence of dynamic storage modulus and loss tangent of OS-TPUs coincided with those of PP-TPUs at polymerization temperature above 190°C. The apparent shear viscosity for OS- and PP-TPUs polymerized above 190°C approached a Newtonian behavior at low shear rates regardless of the polymerization method. These results indicate that TPUs polymerized at higher temperatures form almost the same molecular aggregation structures irrespective of the dynamic polymerization method.

DOI： 10.1002/polb.21080

Language：English  

Norbornane diisocyanate (NBDI: 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane) is a new commercialized diisocyanate. NBDI-based polyurethane elastomers (PUEs) were prepared from poly(oxytetramethylene) glycol (PTMG), NBDI and 1,4-butanediol (BD) by a prepolymer method. Microphase-separated structure and mechanical properties of the NBDI-based PUEs were compared with general aliphatic and cycloaliphatic diisocyanate-based PUEs. The diisocyanates used were isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (HMDI) and 1,6-hexamethylene diisocyanate (HDI). Regular polyurethanes were also prepared as hard segment models from each isocyanate and BD to understand the feature of each hard segment chain. The HDI-based PUE showed the largest Young's modulus and tensile strength in the four PUEs due to the ability of crystallization of the hard segment component and the strongest microphase separation. HMDI has both properties of aliphatic and cycloaliphatic diisocyanates because of its high symmetrical chemical structure compared with NBDI and IPDI. On the other hand, the NBDI- and IPDI-based PUEs have an inclination to phase mixing, leading to decreased Young's modulus and tensile strength. The NBDI-based PUE exhibited better thermal properties at high temperatures due to stiff structure of NBDI.

DOI： 10.1016/j.polymer.2006.12.057

Language：English  

Biogels and bio-hybrid gels were prepared from myofibril of fish and their properties were evaluated. The muscular protein used was extracted from fish meat. After washing and centrifugal separation, the muscular protein was mixed with 3 wt % of NaCl and the gels were prepared by heating the mixtures from 50 to 90 °C. The bio-hybrid gels were prepared from fish protein gel and poly(vinyl alcohol). Tensile tests revealed that the tensile strength, strain at break and Young's modulus of heated hybrid gels prepared at 50, 80 and 90 °C increased with increasing preparation temperature. This can be explained by the difference in crosslinking density. Also, the heated gels showed a good response to electric field in acid and alkaline solutions. Young modulus, tensile strength and elongation at break of the bio-hybrid gels increased with an increasing PVA content. Bending of hybrid gels in solutions of various pH under the electric stimulus was observed. The largest bending angle was 20-30 °C at pH=1.2.

DOI： 10.1007/s00289-006-0612-5

Language：English  

A diisocyanate baring ether bonds, 1,2-bis(isocyanate)ethoxyethane (TEGDI), was used for the preparation of polyurethane elastomers (PUEs). The PUEs were synthesized with either TEGDI or HDI, poly(oxytetramethylene) glycol (PTMG), and curing agents by a prepolymer method. 1,6-Hexamethylene diisocyanate (HDI) was also used as a control diisocyanate. The TEGDI-based PUEs exhibited highly softened property on account of flexibility of TEGDI itself and weaker phase separation. Another TEGDI-based PUEs were prepared with either poly(oxypropylene) glycol (PPG) or poly(caprolactone) glycol (PCL). Microphase-separated structure of these TEGDI-based PUEs are quite different from those with general diisocyanates and the PUEs were made be greatly softened.

DOI： 10.1016/j.polymer.2005.09.009

Language：English  

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.

DOI： 10.1016/j.cis.2004.09.007

Language：English  

Randomly copolymerized poly(carbonate) glycols were employed as starting materials for the synthesis of polyurethane elastomers (PUEs). The poly(carbonate) glycols had hexamethylene (C₆) and tetramethylene (C₄) units between carbonate groups in various composition ratios (C₄/C₆ = 0/100, 50/50, 70/30, and 90/10), and the number-average molecular weights of these poly(carbonate) glycols were 1000 and 2000. The PUEs were synthesized with these poly(carbonate) glycols, 4,4′-diphenyl-methane diisocyanate, and 1,4-butanediol by a prepolymer method. Differential scanning calorimetry measurements revealed that the difference between the glass-transition temperature of the soft segment in the PUEs and the glass-transition temperature of the original glycol polymer decreased and the melting point of the hard-segment domain increased with an increasing C₄ composition ratio. The microphase separation of the polycarbonate) glycol-based PUEs likely became stronger with an increasing C₄ composition ratio. Young's modulus of these PUEs increased with an increasing C₄ composition ratio. This was due to increases in the degree of microphase separation and stiffness of the soft segment with an increase in the C₄ composition ratio. The molecular weight of poly(carbonate) glycol also influenced the microphase-separated structure and mechanical properties of the PUEs. The addition of different methylene chain units to poly(carbonate) glycol was quite effective in controlling the microphase-separated structure and mechanical properties of the PUEs.

DOI： 10.1002/polb.20303

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：English  

Effect of side methyl and dimethyl groups of soft segment component on polyurethane elastomers (PUEs) was investigated with and without elongation. The polymer glycols used were poly(oxytetramethylene) glycol (PTMG), PTMG with dimethyl groups (PTG-X) and methyl groups (PTG-L). Phase separation of the PUEs became weaker with an increasing methyl group content. Tensile test revealed that the increasing methyl group concentration made the PUEs be soften and weaken. The PTMG based PUEs obviously exhibited elongation-induced crystallization during elongation process. In contrast, for the PTG-L and PTG-X based PUEs, crystallinity decreased with an increasing side methyl group content, and the PUEs with PTG-L and PTG-X with highest methyl group content did not crystallize. We succeeded the control of the crystallization behavior of elastomers under an elongation by the introduction of side methyl groups.

DOI： 10.1016/j.polymer.2004.09.061

Language：English  

A novel diisocyanate, 1,2-bis(isocyanate)ethoxyethane (TEGDI), whose backbone is ether bonds was used for the preparation of polyurethane elastomers (PUEs). 1,6-Hexamethylene diisocyanate (HDI) was also used as a control. The PUEs were prepared with either TEGDI or HDI, poly-(oxytetramethylene) glycol (PTMG), and curing agent by a prepolymer method. Differential scanning calorimetry, infrared spectroscopy, and wide-angle X-ray diffraction revealed that the phase separation of the network TEGDI-based PUEs was much weaker compared with that of the HDI ones. Highly softened TEGDI-based PUEs were successfully prepared on account of flexibility of TEGDI itself and weaker phase separation.

DOI： 10.1021/ma0359988

Language：English  

Functionally graded polyurethane elastomers (FGPUEs) were prepared with two molds fixed at different temperatures (30 and 150°C). The effects of the molar ratio of the curing agent (60/40, 75/25, or 97/3 1,4-butane diol/1,1,1-trimethylol propane) and the molecular weight of the polymer glycol (number-average molecular weight = 2000 or 3000) on the molecular aggregation state and mechanical properties of the FGPUEs were investigated with differential scanning calorimetry, polarized optical microscopy, dynamic viscoelastic measurements, and tensile tests. The aggregation state of the FGPUEs was changed continuously from the one side (lower temperature side) to the other side (higher temperature side); for example, the glass-transition temperature gradually increased in this direction. Also, the number of spherulites formed in the FGPUEs increased in the same manner. In the mechanical tests, the tensile strength and elongation at break of the lower temperature side were higher than those of the higher temperature side. This was correlated with the strong phase separation of the lower temperature side. The poly(oxytetramethylene glycol)-based FGPUE with a chain extender of 75 wt% showed the largest degree of the temperature gradient.

DOI： 10.1002/polb.10628

Language：English  

Well-defined poly(methyl methacrylate) (PMMA) brush layers were prepared onto silicon wafers by surface-initiated atom transfer radical polymerization using 2-(4-chlorosulfonylphenyl)-ethyltrichlorosilane as an initiator. Based on molecular weight and layer thickness measurements, it was deduced that the apparent graft density was 0.6-0.8 chains nm^-2 depending on the polymerization time and that the conformation of tethered chains was highly extended. Surface relaxation behavior of the PMMA brush layer and the spin-coated PMMA film was examined by lateral force microscopy. The α_a- and β-relaxation processes were discernibly observed at both surfaces. Although surface molecular motion of the brush layer and the spin-coated film was markedly different from the bulk one, both were hardly distinguishable in terms of relaxation phenomena.

DOI： 10.1295/polymj.35.44

Language：English  

Nanotribological behaviors of organosilane monolayers prepared by the Langmuir-Blodgett (LB) and chemisorption methods are discussed in terms of their aggregation states. Aggregation structure of the LB n-octadecyltrichlorosilane (OTS-C18) monolayers changed from a rectangular to an amorphous phase via a hexagonal phase with increasing temperature. A distinct lateral force decrease accompanies the phase transition. The LB alkyltrichlorosilane monolayers with longer alkyl chains were in a crystalline state at 293K. The lateral force of the LB alkyltrichlorosilane monolayers at 293K increased with increasing chain length. The n-triacontyltrichlorosilane LB monolayer (TATS-C30) in a rectangular phase showed higher lateral force than that of the alkyltrichlorosilane with shorter alkyl chains in a hexagonal phase. The lateral force of the OTS-C18 monolayer prepared by the LB method was higher than that of the chemisorbed one because of the higher packing density of alkyl chain for the LB monolayer, though both monolayers are in a hexagonal phase at 293K. A large increase in lateral force was observed for the 18-nonadecenyltrichlorosilane (NTS) after oxidation of vinyl end groups.

DOI： 10.1016/S0304-3991(02)00100-6

Language：English  

Dielectric measurement in the range 0.1 Hz to 1 MHz were used to study the motions of polymers and ions in an ion-conducting polymer, polypropylene oxide containing small quantities (on the order of 1%) of lithium ions (LiClO₄), confined as a sandwich of uniform thickness between parallel insulating mica surfaces. In the dielectric loss spectrum, we observed three peaks; they originated from the normal mode of the polymer, segmental mode of the polymer, and ion motions. With decreasing film thickness, the peak frequencies corresponding to the normal mode and ion motion shifted to lower frequencies, indicating retardation due to confinement above 30 nm. This was accompanied by diminished intensity of the dielectric normal-mode relaxation, suggesting that confinement diminished the fluctuations of the end-to-end vector of the chain dipole in the direction between the confining surfaces. On the contrary, the segmental mode was not affected at that thickness. Finally, significant retardation of the segmental mode was observed only for the thinnest film (14 nm). The different dynamical modes of the polymer (segmental and slowest normal modes) respond with different thickness and temperature dependence to confinement.

DOI： 10.1140/epje/i2001-10090-x

Language：English  

The n-octadecyltrichlorosilane (OTS, CH₃(CH₂)₁₇SiCl₃), 18-nonadecenyltrichlorosilane (NTS, CH₂.CH(CH₂)₁₇SiCl₃), [2-(perfluorooctyl)ethyl]trichlorosilane (FOETS, CF₃(CF₂)₇CH₂CH₂SiCl ₃) monolayers, and their mixed monolayers were used as model surfaces for the study of protein adsorption mechanism. Surface plasmon resonance (SPR) spectroscopy was applied to analyze the protein adsorption behavior onto the monolayer surfaces. The surfaces after exposure of these monolayers to bovine serum albumin (BSA) and γ-globulin(IgG) solutions were observed with atomic force microscope(AFM). AFM observation revealed that the charged protein either below or above pI was preferentially adsorbed onto the FOETS phase of the phase-separated (OTS/FOETS) mixed monolayer. in situ AFM observation of monolayer surfaces in BSA solution also revealed the preferential adsorption of BSA onto the hydrophobic FOETS surface. SPR clarified that the amount of adsorbed protein in the charged state was lower than that in the neutral state. Adhesion force was not detected in the force-distance curve measurement between negatively-charged HOOC(CH₂)₉SH chemisorbed cantilever tip and the OTS phase in the presence of adsorbed BSA on FOETS phase of mixed monolayer. These results indicate that the preferential adsorption of protein onto the FOETS phase for the mixed monolayer systems at either below or above pI is due to, (1) the minimization of interfacial free energy between the monolayer surface and the buffer solution; and (2) the electrostatic repulsion among protein molecules bearing charges.

DOI： 10.1016/S0927-7765(01)00231-4

Language：English  

A novel and convenient method to prepare organosilane monolayers was proposed. Pure water was put onto a cleaned silicon wafer and then a toluene solution of n-trichloro(octadecyl)silane (OTS) was spread on it. X-ray photo-electron spectroscopy and atomic force microscopic observation revealed that an OTS monolayer was successfully formed on the solid substrate after the water was evaporated. The static water contact angle of the silicon wafer covered with the OTS monolayer was 105°. Molecular aggregation states of the OTS monolayer were examined by electron diffraction, Fourier transform infrared spectroscopic, X-ray reflectivity, and grazing incidence X-ray diffraction measurements. The prepared OTS monolayer was in a two-dimensional hexagonal crystalline state at 293 K and alkyl chains of the OTS molecules were oriented normal to the surface. Also, the alkyl chains in the monolayer were highly ordered, although the experimental procedure for the monolayer preparation was quite simple. The development of this novel method to prepare a low energy surface will contribute to the material science as well as having industrial applications.

DOI： 10.1246/bcsj.74.1397

Language：English  

Scanning probe microscopy (SPM) techniques are used to characterize surfaces related to the processing of benzocyclobutene (BCB) dielectric thin films. Thermally cured resins and photodefineable resins are sold under the trade name CYLCOTENE™ ¹⁾ for electronic applications. TappingMode AFM (TMAFM) imaging is used to follow changes in adhesion promoter morphology upon baking to help explain adhesion performance. Power spectral density (PSD) analysis of TMAFM images of plasma treated BCB surfaces are unique and can be used to 'fingerprint' processes. Selective oxidation of the BCB surface can be used to fabricate a phase imaging standard for TMAFM. Near surface modulus of the BCB materials is 3.6 ± 0.2 GPa and the hardness is 0.38 ± 0.2 GPa measured by depth-sensing nanoindentation. Creep recovery of indents can be used to qualitatively distinguish between thermal and photocureable materials. A heated tip in a scanning thermal microscope can induce the thermal curing of BCB over micron sized areas. Local thermal analysis with the same probe allows the measurement of the changes in the glass transition, T _g, at the surface with cure temperature.

DOI： 10.1002/1521-3900(200103)167:1<213::AID-MASY213>3.0.CO;2-D

Language：English  

Crystal transition behavior of lignoceric acid (LA) monolayer was structurally investigated by electron diffraction (ED) in conjunction with scanning force microscopy (SFM). LA molecules form two-dimensional hexagonal crystallites right after one spreads a solution at the air/water interface. The hexagonal-rectangular transition of the LA monolayer was attained by two different experimental procedures: monolayer compression under an isothermal condition and monolayer cooling under an isobaric condition. In the compression process, the hexagonal and rectangular phases coexisted in the monolayer at the surface pressure, π, of 10 mN m^-1, which was slightly lower than the plateau pressure, and the subphase temperature of 293 K. When the π exceeded the plateau pressure, the hexagonal phase in the LA monolayer was entirely transformed to the rectangular one. High-resolution SFM showed that the crystal transition from the hexagonal to rectangular phase proceeded via a quasi-disordered phase upon compression. A similar hexagonal-rectangular transition was also observed during the monolayer cooling process at the π of 15 mN m^-1. Based on SFM observation, we claimed that the molecular ordering or packing state in the rectangular lattice induced by cooling was better than that by the monolayer compression. Finally, the crystal transition mechanisms for these two procedures were proposed.

DOI： 10.1246/bcsj.74.765

Language：English  

The n-octadecyltrichlorosilane (OTS, CH₃(CH₂)₁₇SiCl₃), 18-nonadecenyltrichlorosilane (NTS, CH₂=CH(CH₂)₁₇SiCl₃), [2-(perfluorooctyl)ethyl] trichlorosilane (FOETS, CF₃(CF₂)₇CH₂ CH₂SiCl₃) monolayers, and their mixed monolayers were used as the model substrates for the study of protein adsorption mechanism. Surface plasmon resonance (SPR) spectroscopy was applied to analyze the protein adsorption behavior onto the surface of the monolayers. Atomic force microscope (AFM) was used to observe the monolayer surfaces after exposure of these monolayers to bovine serum albumin (BSA) and Δ-globulin(IgG) solution. AFM observation revealed that the charged protein either below or above the isoelectric point was preferentially adsorbed onto the FOETS phase of the (OTS/FOETS) mixed monolayer. SPR revealed that the amount of adsorbed protein in the charged state was lower than that in the neutral state. These results indicate that the preferential adsorption of protein onto the FOETS phase for the mixed monolayer systems at either below or above pI is due to (1) the minimization of interfacial free energy between the monolayer surface and the buffer solution, and (2) the electrostatic repulsion among protein molecules bearing charges.

DOI： 10.1002/1521-3900(200103)167:1<271::AID-MASY271>3.0.CO;2-Y

Language：English  

Stable fluoroalkyl, alkyl and mixed fluoroalkyl/alkyl monolayers were prepared on solid substrates by the Langmuir method. The n-octadecyltrichlorosilane (OTS), 18-nonadecenylrichlorosilane (NTS) and [3-(perfluorododecyl)propyloxy]triethoxysilane (FDOPTES) in monolayers were in a crystalline state at 293 K, as by electron diffraction (ED) studies. In contrast, the n-dodecyltrichlorosilane (DDTS) and [2-(perfluorooctyl)ethyl] -trichlorosilane (FOETS) monolayers with shorter hydrophobic chains were in an amorphous state at 293 K. Molecular images of the crystalline OTS and FDOPTES monolayers were acquired with high-resolution atomic force microscopy (AFM). The direct observation of the molecular arrangement of the crystalline OTS and FDOPTES was successfully achieved The (10) spacings for these monolayers corresponded well to the cross section area of the alkyl and fluoroalkyl chains. It was revealed from the contact angle measurements that the magnitudes of surface free energies of the fluoroalkylsilane monolayers were higher than of the alkylsilane monolayers. The surface free energy of the crystalline fluoroalkylsilane monolayer (FDOPTES monolayer) was higher than that of the amorphous monolayers due to high orientation of the fluoromethyl end groups at the monolayer surface. AFM observation revealed that the (crystalline OTS/amorphous FOETS) mixed monolayer was in a phase-separated state due to the crystallization of the OTS molecules. The (crystalline NTS/amorphous FOETS) mixed monolayer also showed a phase separation. By oxidation of the NTS phase in the (NTS/FOETS) mixed monolayer, a phase-separated structure with large suface energy gap can be constructed. The surface properties of the mixed monolayer was evaluated based on lateral force microscopy (LFM) and adhesion force measurement. Literatures cited.

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：English  

Relationships between the molecular aggregation state and the molecular motion of organosilane monolayers with various chain lengths prepared by the Langmuir-Blodgett (LB) method were investigated by lateral force microscopic, Fourier transform-infrared (FT-IR) spectroscopic, and electron diffraction (ED) measurements. The lateral force of the organosilane monolayers increased with increasing their chain length. This is mainly because the intermolecular cohesive energy is proportional to the number of carbons in a chain. The lateral force of the alkylsilane monolayer was compared with that of the fluoroalkylsilane monolayer for the corresponding alkyl chain length. Consequently, the fluoroalkylsilane monolayer showed higher lateral force than the alkylsilane one. Temperature-dependent ED and FT-IR measurements revealed that the molecular aggregation state of the n-octadecyltrichlorosilane (OTS) monolayer changed from the rectangular lattice to the amorphous state via the hexagonal lattice with increasing temperature. The transition temperatures, rectangular to hexagonal and hexagonal to amorphous, were found to be 240 and 333 K, respectively. The distinct lateral force decrease was concurrently observed for the OTS monolayer at 240 and 333 K. The remarkable decrement of the lateral force at 240 K might be attributed to the decreasing molecular density and the activation of molecular motion (rotational motion along the molecular axis) owing to the rectangular-hexagonal crystal transition. And, the second remarkable depression of the lateral force observed at 333 K might come from the activation of thermal molecular motion due to the melting of alkyl chains.

DOI： 10.1021/la0004303

Language：English  

The n-octadecyltrichlorosilane (OTS) monolayer was prepared by the Langmuir-Blodgett method. The formation mechanism of the OTS monolayer on the water subphase was investigated on the basis of electron diffraction (ED) study, Fourier transform infrared external reflection spectroscopic (FT-IR/ERS) measurement and high-resolution atomic force microscopic (AFM) observation. Morphological changes in the monolayer in a compression process were observed by AFM. FT-IR/ERS measurement was performed for the monolayer at the air/water interface, and that the ED and AFM observations were done for the monolayer transferred onto substrate. ED study and high-resolution AFM observation revealed that the OTS monolayer was in a crystalline state at 293 K. Also, FT-IR/ERS measurement and AFM observation showed that the OTS molecules crystallize and polymerize spontaneously right after spreading a toluene solution of OTS on the water subphase. Then, during a monolayer compression, the crystalline OTS monolayer domain did not form the larger ones by sintering at the crystalline domain interface at 293 K. Also, AFM and ED observations revealed that the defect-diminished OTS monolayer could be successfully prepared by using the multi-step creep method.

DOI： 10.1016/S0927-7757(00)00444-1

Language：English  

A comparative study in molecular arrangements of the n-octadecyltrichlorosilane (OTS) monolayer prepared by the Langmuir method and the chemisorption methods were carried out on the basis of grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XR) measurements. The OTS molecules in the Langmuir OTS monolayer uniformly tilt ca. 8-10° to the surface normal and packed in a hexagonal lattice with the (10) spacing of 0.412 nm. On the other hand, the OTS molecules in the chemisorbed OTS monolayer tilt ca. 15-17° to the surface normal and also crystallite orient randomly in the two-dimensional plane. The average magnitude of the (10) spacing of the chemisorbed OTS monolayer was ca. 0.417 nm. Direct evidence that the packing density of the Langmuir OTS monolayer was higher than that of the chemisorbed OTS monolayer was obtained by GIXD and XR measurements for the first time.

DOI： 10.1021/la9909042

Language：English  

A mixed (n-octadecyltrichlorosilane (OTS)/[2-(perfluorooctyl)ethyl]trichlorosilane (FOETS)) monolayer was prepared on the water subphase and was subsequently immobilized onto the silicon wafer surface by chemical bonds. Atomic force microscopic (AFM) observation of the mixed (OTS/FOETS) monolayer revealed the formation of a phase-separated structure. In situ AFM observation of the adsorption behavior of bovine serum albumin (BSA) onto the mixed (OTS/FOETS) monolayers, successfully showed the adsorption behavior of BSA onto the phase-separated surface. It also revealed that in the case of pH 7.5, BSA was preferentially adsorbed onto the lower surface free energy FOETS phase of the mixed (OTS/FOETS) monolayer. On the other hand, BSA was adsorbed homogeneously onto the OTS and FOETS phases at the isoelectric point of BSA (pI 4.7). These results indicate that the preferential adsorption of BSA onto the FOETS phase in the mixed (OTS/FOETS) monolayer system may be due to: (1) the minimization of interfacial free energy between a monolayer surface and an aqueous solution; and (2) the electrostatic repulsion among BSA molecules bearing negative charges.

DOI： 10.1163/156856200743535

Language：English  

The 18-nonadecyltrichlorosilane (NTS) monolayer with a vinyl end group was prepared by the Langmuir method. The monolayer with a hydrophilic carboxylated surface was subsequently obtained by oxidation of the vinyl end group. For the multilayer preparation, the NTS monolayer was immobilized onto the hydrophilic carboxylated NTS (NTS_COOH) monolayer. The NTS multilayer film was obtained by repetitions of depositions and oxidations. Aggregation structure of the NTS multilayer film was evaluated on the basis of X-ray reflectivity (XR), Brewster angle infrared (IR) spectroscopic measurements, electron diffraction (ED) and atomic force microscopic (AFM) observations. It was revealed that the NTS multilayer film with a well-ordered structure could be prepared by the Langmuir method. The local height control was performed by utilizing the phase-separated mixed monolayer being composed of the NTS and [2-(perfluorooctyl)ethyl]trichlorosilane (FOETS) molecule. The (NTS/FOETS) mixed monolayer showed phase-separated structure like sea-island, whose domain and matrix phases were composed of crystalline NTS and amorphous FOETS molecules, respectively. The (NTSCooH/FOETS) mixed monolayer with the hydrophilic domain and the hydrophobic matrix was obtained by selective oxidization of the NTS phase in the (NTS/FOETS) mixed monolayer. Furthermore, the local height control on the NTS_COOH phase of the (NTS_COOH/_FOETS) mixed monolayer was performed by chemisorption of NTS from the solution. The height increase in the NTS_COOH phase was confirmed by AFM and lateral force microscopy (LFM).

Language：English  

Organochlorosilane monolayers were polymerized on the water surface and immobilized onto the silicon wafer surface by Langmuir method. The electron diffraction (ED) pattern of the n-octadecyltrichlorosilane(OTS) monolayer revealed that OTS molecules were regularly arranged in a hexagonal array with the (10) spacing of ca. 0.42 nm. On the other hand, ED study revealed that the [2-(perfluorooctyl)ethyl]trichlorosilane (FOETS) monolayer was amorphous state at room temperature. The high-resolution atomic force microscopic (AFM) image of the OTS monolayer in a scan area of 10×10 nm² exhibited the individual methyl groups of which packing was a hexagonal array in a similar molecular arrangement concluded by the ED study. AFM observation of the (OTS/FOETS) mixed monolayer revealed that the crystalline OTS circular domains of ca. 1-2 μm in diameter were surrounded by a sea-like amorphous FOETS matrix, even though the molar fraction of OTS was above 75%. Phase separation was observed for monolayer prepared from FOETS and non-polymerizable and crystallizable amphiphile such as lignoceric acid (LA). The phase separation of the (alkylsilane/fluoroalkylsilane) mixed monolayer might be attributed to both the crystallizable characteristics of alkylsilane molecules and faster spreading of FOETS molecules on the water surface. The mixed monolayer of crystalline alkylsilane (OTS) and amorphous alkylsilane (n-dodecyltrichlorosilane, DDTS) formed phase-separated structure on the water surface because of the crystallizable characteristics of OTS. Lateral force microscopic (LFM) observation revealed that the order of the magnitude of lateral force generated against the silicon nitride tip was crystalline Si substrate >crystalline n-triacontyltrichlorosilane (TATS) domain> crystalline n-dococyltrichlorosilane (DOTS) domain> amorphous FOETS matrix > crystalline OTS domain>amorphous DDTS matrix. On the other hand, scanning viscoelasticity microscopic observation revealed that the order of the magnitude of modulus was Si substrate > crystalline OTS domain > amorphous FOETS matrix.

Language：English  

Language：English  

Molecular arrangement of polymerized n-octadecyltrichlorosilane (OTS, CH₃(CH₂)₁₇SiCl₃) monolayer transferred onto hydrophilic substrate by an upward drawing method was investigated with a transmission electron microscope (TEM) and an atomic force microscope (AFM). The electron diffraction (ED) pattern of the OTS monolayer revealed that the OTS molecules were regularly arranged in a hexagonal array with a (10) spacing of ca. 0.42 nm. The high-resolution AFM image of the OTS monolayer in a scan area of 10 × 10 nm² exhibited the individual methyl group of which packing was a hexagonal array in a similar molecular arrangement concluded on the basis of the ED study. Also, the point defect in the crystalline OTS monolayer was successfully observed for the first time.

DOI： 10.1021/la970040p

Language：English  

Octadecyltrichlorosilane (OTS) and [2-(perfluorooctyl)ethyl]trichlorosilane (FOETS) monolayers and their mixed monolayer were polymerized on a water subphase and subsequently immobilized onto a silicon wafer surface by covalent bonding. Atomic force microscopic (AFM) observation of the mixed (OTS/FOETS) monolayer revealed the formation of a phase-separated structure. Protein-adsorption behavior onto the monolayers was investigated in situ on the basis of an attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopic flow cell method and the morphology of the monolayer surface-adsorbed bovine serum albumin (BSA) was observed by AFM. Protein adsorption behavior observed by ATR-FT-IR flow cell method revealed that the amount of BSA adsorption onto the OTS and FOETS monolayers increased remarkably at an initial experimental stage and attained a steady state within a few minutes at pH 7.5. The amount of steady state adsorption was c. 0.18-0.2 μgcm^-2. AFM observation of the monolayer after exposure to BSA solution suggested that BSA adsorbed in the end-on adsorption state on OTS monolayer and side-on one in the FOETS monolayer, respectively. However, in the case of the mixed (OTS/FOETS) monolayer, ATR-FT-IR flow cell experiment revealed that the amount of steady state adsorption of BSA was suppressed. Also, AFM observation revealed that at pH 7.5, BSA preferentially adsorbed onto the FOETS phase of the mixed (OTS/FOETS) monolayer, which had a higher interfacial free energy against water. On the other hand, BSA adsorbed homogeneously onto the OTS and FOETS phases at the isoelectric point of BSA (pH 4.7). These results indicate that the preferential adsorption of BSA onto the FOETS phase in the mixed (OTS/FOETS) monolayer system is due to: (1) the minimization of the interfacial free energy between a monolayer surface and an aqueous solution; and (2) the electrostatic repulsion between BSA molecules bearing negative charges.

DOI： 10.1163/156856298X00479

Language：English  

The n-octadecyltrichlorosilane (OTS) and the [2-(perfluorooctyl)ethyl]trichlorosilane (FOETS) monolayers, and their mixed monolayer were used as the model systems for the study of protein adsorption behavior because of their remarkable surface stability. The attenuated total reflection infrared (ATR-FT-IR) flow cell studies revealed that the adsorption amount of bovine serum albumin (BSA) onto each OTS and FOETS monolayer steeply increased in an initial stage of adsorption experiment and attained an equilibrium within a few minutes at pH 7.5. In the case of the (OTS/ FOETS) (50/50 mol/mol) mixed monolayer, the amount of protein adsorption was suppressed. AFM observation in a BSA solution at pH 7.5 revealed that BSA was preferentially adsorbed onto the FOETS phase of the (OTS/FOETS) mixed monolayer, while selective adsorption of BSA onto the FOETS phase was not observed at the isoelectric point of BSA (pH 4.7). Furthermore, [(3-mercaptopropyl)trimethoxysilane (MTS)/FOETS] mixed monolayer with reactive -SH group in domain was prepared. Then, the BSA was selectively immobilized onto the MTS phase.

DOI： 10.1295/koron.55.344

Language：English  

(Alkylsilane/fluoroalkylsilane) mixed monolayers were immobilized covalently on a silicon wafer surface with stable surface structure. Atomic force microscopic observation of the n-octadecyltrichlorosilane(OTS)/[2-(perfluorooctyl)ethyl]trichlorosila ne (FOETS) mixed monolayer revealed that the crystalline OTS circular domains of ca. 1-2 μm in diameter were surrounded by a sea-like amorphous FOETS matrix, even though the molar fraction of OTS was above 75%. Also, the phase-separated monolayer can be prepared from FOETS, and a non-polymerizable and crystallizable amphiphile such as lignoceric acid (LA). The phase separation of the (alkylsilane/fluoroalkylsilane) mixed monolayer might be attributed to both faster spreading of FOETS molecules on the water surface and the crystallizable characteristics of alkylsilane molecules. The mixed monolayer of crystalline alkylsilane (OTS) and amorphous alkylsilane (n-dodecyltrichlorosilane, DDTS) formed a phase-separated structure on the water surface because of the crystallizable characteristics of OTS. Lateral force microscopic (LFM) observation revealed that the order of the magnitude of lateral force generated against the silicon nitride tip was: n-triacontyltrichlorosilane (TATS) domain with longer alkyl chain>amorphous FOETS matrix>crystalline OTS domain. On the other hand, scanning viscoelasticity microscopic observation revealed that the order of the magnitude of modulus was: Si substrate>crystalline OTS domain>amorphous FOETS matrix.

DOI： 10.1016/0968-5677(96)00024-7

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Number of participants：250

Type：Competition, symposium, etc. 

Number of participants：200

Type：Competition, symposium, etc. 

Number of participants：450

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：3,000

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Number of participants：690

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：10,000