Kyushu University Academic Staff Educational and Research Activities Database
List of Reports
Daisuke Kawaguchi Last modified date:2022.01.15

Associate Professor / Department of Applied Chemistry / Faculty of Engineering

1. Daisuke Kawaguchi, Direct Observation and Mutual Diffusion of Cyclic Polymers, Polymer Journal 45, 2013.08.
2. D. KAWAGUCHI, A. TAKANO, Y. MATSUSHITA, Molecular Characterization and Interdiffusion of Ring-shaped Polystyrenes and Their Derivatives, AES Technical Reviews Part A, 2008.05.
3. Aggregation States and Dynamics of Polymer Chains at Model Interfaces with Inorganic Fillers

The performance of a polymer composite material, in which inorganic fillers are dispersed, is closely related to the aggregation states and dynamics of polymer chains at the interface with the filler. In this short review, we first introduce the relaxation behavior of polymer chains in thin films supported on solid substrates, suggesting that the surface and interfacial dynamics are faster and slower than that in the bulk. Then, aggregation states and dynamics of rubbery chains as well as glassy ones are directly discussed on the basis of the interfacial sensitive vibrational spectroscopy. We clearly demonstrate that chains at the substrate interface can be hardly relaxed even at a temperature being far above the bulk glass transition temperature. Finally, we try to combine this knowledge with the viscoelastic properties of bulk composite materials composed of a rubbery polymer and an inorganic filler.

4. Structures and Physical Properties at Surfaces and Interfaces of Polymers.
5. T Kajiyama, D Kawaguchi, K Tanaka, Polymer chain diffusion at a temperature below its bulk glass transition temperature, CHINESE JOURNAL OF POLYMER SCIENCE, Vol.21, No.2, pp.141-146, 2003.03, In this study, it was examined whether the dynamics of polymer chains at a surface is different from that in the bulk, and if so, to what extent they differ in terms of surface glass transition temperature and diffusion coefficient. Obtained results clearly indicate that surface chains can travel for a relatively large distance in comparison with the characteristic length scale of usual segmental motion even at a temperature below its bulk glass transition temperature, T-g(b). This is consistent with our previous results that the surface glass transition temperature is much lower than the corresponding T-g(b). Also, it was experimentally revealed that there was a gradient of molecular motion in the surface region..
6. Tisato Kajiyama, Daisuke Kawaguchi, Atsushi Sakai, Noriaki Satomi, Keiji Tanaka, Atsushi Takahara, Determination Factors on Surface Glass Transition Temperatures of Polymeric Solids, High Performance Polymers, 10.1088/0954-0083/12/4/314, Vol.12, No.4, pp.587-597, 2000.12, The surface molecular motion of monodisperse proton-terminated polystyrene (PS-H), α, ω-diamino-terminated PS ( α, ω-PS(NH2)2) and α, ω-dicarboxy-terminated PS ( α, ω-PS(COOH)2) films was studied by scanning viscoelasticity microscopy in conjunction with lateral force microscopy. The glass transition temperature Tg, at the surface, Tgs was found to be markedly lower than bulk Tg, Tgb, and the number-average molecular weight, Mn, dependence of Tgs more remarkable than that of Tgb. Also, the magnitude of Tgs was strongly dependent on the chain end chemistry. Hence, the activation of surface molecular motion was explained in terms of an excess free volume induced by the preferential surface segregation of chain end groups. The chain end segregation at the film surface was confirmed by dynamic secondary ion mass spectroscopic measurement. However, the Tgs for the PS-H with quasi-infinite Mn was lower than the corresponding Tgb, even though the number density of chain ends was almost negligible. In addition, Tgs for PS films with hydrophilic chain ends, which might be depleted at the film surface, were lower than the bulk values. The apparent activation energy for the surface micro-Brownian motion corresponding to the αa-relaxation process was approximately half of the bulk value. Finally, the depression of Tgs in comparison with Tgs is discussed on the basis of several factors, such as a decreased segment size of molecular motion for the surface αa-relaxation process due to the existence of the free space on the polymer surface and/or a reduced chain entanglement at the surface, in addition to the chain end effect..