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Photo‐alignment of low‐molecular liquid crystals on photo‐crosslinkable polymer liquid crystalline film by linearly polarised UV light
Author(s) -
Kawatsuki Nobuhiro,
Takatsuka Hirofumi,
Kawakami Yuya,
Yamamoto Tohei
Publication year - 1999
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/(sici)1099-1581(199907)10:7<429::aid-pat888>3.0.co;2-y
Subject(s) - homeotropic alignment , liquid crystal , materials science , mesogen , irradiation , polymer , perpendicular , intensity (physics) , optics , homogeneous , optoelectronics , light intensity , liquid crystalline , composite material , physics , geometry , mathematics , nuclear physics , thermodynamics
Effects are described of the intensity and irradiation temperature of a linearly polarized (LP) UV light on a photoreaction of a photo‐crosslinkable polymer liquid crystal (PLC) film comprising a cinnamoylethoxybiphenyl side group, and the photo‐alignment behavior of nematic low‐molecular (LM) liquid crystals (LCs) on a PLC film. Both homeotropic and homogeneous alignments of the LM‐LC were possible on the photoreacted PLC film when the film was irradiated at room temperature. However, a homeotropic alignment was not observed when the film was exposed in the liquid crystalline temperature range of the PLC. When the light intensity was strong, the homogeneous alignment direction can be controlled both parallel and perpendicular to the electric vector ( t E ) of the incident LP‐UV light, while it needed a large amount of irradiation energy to obtain a perpendicular alignment for the weak LP‐UV irradiation. The LM‐LC alignment behavior can be explained by a change of the interaction among the LM‐LC, the photo‐crosslinked mesogenic group of the PLC film and the photoinduced alignment of the photoreacted PLC film. Copyright © 1999 John Wiley & Sons, Ltd.