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A High‐Density Azobenzene Side Chain Polymer Brush for Azimuthal and Zenithal Orientational Photoswitching of a Nematic Liquid Crystal
Author(s) -
Mukai Koji,
Imai Kenjiro,
Hara Mitsuo,
Nagano Shusaku,
Seki Takahiro
Publication year - 2019
Publication title -
chemphotochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 18
ISSN - 2367-0932
DOI - 10.1002/cptc.201800234
Subject(s) - azobenzene , homeotropic alignment , liquid crystal , polymer , materials science , brush , side chain , azimuth , orientation (vector space) , spiropyran , polymer brush , optoelectronics , optics , composite material , polymerization , physics , geometry , mathematics
The azimuthal and zenithal orientational switching of nematic liquid crystals (NLCs) can be performed by photoresponsive azobenzene alignment layers called command surfaces. Such photoresponsive layers have been prepared by molecular assembly methods or by spincasting of polymer materials. This work reports on the photoswitching orientation behavior of an NLC on a high‐density brush of an azobenzene‐containing side chain liquid crystalline polymer. On the high‐density polymer brush surface, the zenithal homeotropic/planar photoalignment switching modes triggered by UV/visible light irradiation are reversed from those observed for traditional command surface systems, reflecting the azobenzene side chain orientation directing parallel to the substrate surface. Because the thermally stable trans ‐azobenzene provides the in‐plane orientation of the NLC, irradiation with linearly polarized visible light readily switches the azimuthal direction to an arbitrary direction, and the resulting orientation is retained persistently. This paper discusses the features of the architecture of a high‐density polymer brush as the command surface for NLC orientation.