@inbook{161624a4c8d740b5827c25eb3e2a7333,
title = "Mobility gradient of polystyrene in films supported on solid substrates",
abstract = "In this review, we show the distribution of glass transition temperature (T g) in monodisperse polystyrene (PS) films coated on silicon oxide layers along the direction normal to the surface. Scanning force microscopy with a lateral force mode revealed that surface T g () was lower than the corresponding bulk T g (). Interestingly, the glass transition dynamics at the surface was better expressed by an Arrhenius equation than by a Vogel-Fulcher-Tamman equation. Interdiffusion experiments for PS bilayers at various temperatures, above and below, enabled us to gain direct access to the mobility gradient in the surface region. T g at the solid substrate was examined by fluorescence lifetime measurements using evanescent wave excitation. The interfacial T g was higher than the corresponding. The extent of the elevation was a function of the distance from the substrate and the interfacial energy. The T g both at the surface and interface was also studied by the coarse-grained molecular dynamics simulation. The results were in good accordance with the experimental results. Finally, dynamic mechanical analysis for PS in thin and ultrathin films was made. The relaxation time for the segmental motion became broader towards the faster and slower sides, due probably to the surface and interfacial mobility. Graphical Abstract:",
author = "Yoshihisa Fujii and Hiroshi Morita and Atsushi Takahara and Keiji Tanaka",
note = "Funding Information: We deeply thank Professor Emeritus Tisato Kajiyama, Professor Emeritus Toshihiko Nagamura, Professor Daisuke Kawaguchi, Dr. Kei-ichi Akabori, and Dr. Yohei Tateishi for their fruitful discussion. This research was partly supported by Grant-in-Aid for Scientific Research (B) (No. 24350061), and for Science Research in a Priority Area “Soft Matter Physics” (No. 21015022) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.",
year = "2013",
doi = "10.1007/12_2012_175",
language = "English",
isbn = "9783642343384",
series = "Advances in Polymer Science",
publisher = "Springer New York LLC",
pages = "1--28",
booktitle = "Glass Transition, Dynamics and Heterogeneity of Polymer Thin Films",
}