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Bistable electro‐optical switching for (liquid crystalline polymer)/(low molecular weight liquid crystal) composite system
Author(s) -
Kikuchi Hirotsugu,
Moritomi Satoru,
Hwang Jenn Chiu,
Kajiyama Tisato
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.1990.220010503
Subject(s) - liquid crystal , materials science , mesophase , electric field , bistability , composite number , mesogen , phase (matter) , polymer , isotropy , dielectric , light scattering , scattering , composite material , condensed matter physics , optics , chemical physics , optoelectronics , liquid crystalline , organic chemistry , chemistry , physics , quantum mechanics
A series of thin films composed of liquid crystalline polymer (LCP) and low molecular weight liquid crystal (LMWLC) was prepared by a solvent‐casting method. LMWLC is miscible over a whole range of LCP concentrations in isotropic and mesomorphic states. The composite system formed a smectic phase in a LCP weight fraction range above 50%. Reversible and bistable electro‐optical effects based on light scattering were recognized for a smectic phase of the binary composite composed of LCP and LMWLC. A light scattering state appeared in the case of application of an a.c. electric field below a threshold frequency (f c ). Furthermore, application of an a.c. field above f c made the transmission light intensity increase. Such phenomena were induced in conjunction with the two types of effect: one is an electric field effect based on the dielectric anisotropy of the mesogenic side chain; and the other is an electric current effect based on the electrohydrodynamic motion of the main chain. In the case of a smectic mesophase, the turbid and transparent states remained unchanged, even though the electric field is removed (memory effect).