Synthesis of Polymer Liquid Crystals Containing Squarylium Dyes

摘要

Dichroic properties of squarylium dyes which dissolved as guest molecules in low-molecular-weight liquid crystal were investigated for the design of novel polymer liquid crystals containing dicroic squarylium dyes. It was found that unsymmetrical squarylium dyes containing a benzothiazole moiety showed the best dichroic ratio and order parameter in low-molecular-weight liquid crystal. As squarylium dye monomers, blue squarylium monomers (3) containing a benzoyl group with an acryloyl group were prepared by the reaction of N-ethylhydroxy derivative of benothiazole-unsymmetrical squarylium dyes with benzoic acid derivative containing an acryloyl group in the presence of 2-chloro-1-methylpyridinium iodide, DMAP, and benzene, at 65 deg C, for 12 h. Novel copolymer liquid crystals with 1.0 or 0.75 squarylium dye content were obtained by copolymerization of blue squarlyium monomers wiht 4-cyanophenyl 4-(6-acryloyloxyhexyloxy)benzoate, as a mesogenic monomer, at 70 deg C for 24 h.