Substrate effect on mechanical relaxation of polystyrene in ultrathin films |
| |
Authors: | K-I Akabori K Tanaka A Takahara T Kajiyama T Nagamura |
| |
Institution: | (1) Department of Applied Chemistry Faculty of Engineering, Kyushu University, 44 Moto-oka, Fukuoka 819-0395, Japan;(2) Institute for Materials Chemistry and Engineering, Kyushu University, 44 Moto-oka, Fukuoka 819-0395, Japan;(3) Kyushu University 44 Moto-oka, Fukuoka 819-0395, Japan |
| |
Abstract: | Mechanical relaxation behavior in ultrathin polystyrene
(PS) films supported on silicon oxide (SiOx) and gold (Au) substrates
has been studied by dynamic viscoelastic measurement. Based on the method,
effects of free surface and substrate interface on the segmental dynamics
were discussed. In the case of thin PS films with a thickness of
approximately 200 nm, αa-relaxation process corresponding to
the segmental motion did not show any deviation from the bulk behavior. In
contrast, for the films thinner than about 50 nm, the relaxation time
distribution for the αa-process became broader, probably due to
a mobility gradient in the surface and interfacial regions. When we
sandwiched an ultrathin PS film between SiOx layers, another relaxation
process, in addition to the original αa-process, appeared at a
higher temperature side that we assigned to the interfacial αa-relaxation
process. However, this was never seen for an ultrathin PS
film between Au layers, implying that restriction from the substrate
interface might be weak in this case. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|