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Reversible alignment change of nematic liquid crystals by photochromic polymer films
Author(s) -
Kawanishi Yuji,
Seki Takahiro,
Tamaki Takashi,
Ichimura Kunihiro,
Ikeda Mitsuhiro,
Aoki Koso
Publication year - 1990
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/pat.1990.220010505
Subject(s) - azobenzene , liquid crystal , materials science , photochromism , photoisomerization , polymer , chromophore , chemical engineering , monolayer , layer (electronics) , polymer chemistry , photochemistry , composite material , organic chemistry , nanotechnology , optoelectronics , chemistry , engineering , catalysis , isomerization
The alignment of a nematic liquid crystal (LC) was changed reversibly by a photochromic reaction of vinyl‐polymer films bearing azobenzene (Az) chromophores. Photoisomerization of Az in the polymer films proceeded slower than in solution systems with an irreversible nature, due to a limited free volume of polymers and the presence of Az aggregates. Photoregulative Az films were obtained by two procedures: (i) spin‐coating followed by baking processes: and (ii) adsorption from a LC/polymer mixture onto a lecithin‐coated glass surface. Perpendicular alignment, which is achieved both in the surface Az and in the LC layer, allows a parallel interaction between them and enables the photoregulation of the LC alignment.