Photoinduced changes of surface order in coumarin side-chain polymer films used for liquid crystal photoalignment

被引：5

作者：

Bergmann, G

Jackson, PO

Hogg, JHC

Stirner, T

O'Neill, M

Duffy, WL

Kelly, SM

Clark, GF

机构：

[1] Univ Hull, Dept Phys, Kingston Upon Hull HU6 7RX, N Humberside, England

[2] Univ Hull, Dept Chem, Kingston Upon Hull HU6 7RX, N Humberside, England

[3] SERC, Daresbury Lab, Warrington WA4 4AD, Cheshire, England

来源：

APPLIED PHYSICS LETTERS | 2005年 / 87卷 / 06期

基金：

英国工程与自然科学研究理事会;

关键词：

D O I：

10.1063/1.2009070

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

Specular x-ray reflectivity probes morphological changes in a crosslinkable coumarin photoalignment polymer film resulting from ultraviolet irradiation. An ordered surface layer with density oscillations compatible with planar side-chain alignment is obtained before irradiation. The ordering is enhanced in the early stages of crosslinking. This is attributed to the photoinduced increase of mobility of the side-chains resulting from the creation of free volume by the crosslinking process. The expansion of the thin film confirms that free volume is created. The surface ordering decreases with prolonged ultraviolet irradiation because of increased material viscosity resulting from a high crosslinked density. The implications of surface ordering on liquid crystal photoalignment are discussed. (c) 2005 American Institute of Physics.

引用

页数：3

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