SYNTHESIS, CHARACTERIZATION AND PHOTOREACTION OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS COMPRISING CINNAMOYL BIPHENYL MESOGEN

Liquid-crystalline (meth)acrylate monomers and polymers having mesogen ic groups based on 4-alkyloxy-4'-cinnamoylbiphenyl (m = 2, 6) were syn thesized. The methacrylate monomers 4c, d were polymerized by free rad ical polymerization. Under the same conditions, the acrylate monomers 4a, b gave unidentified polymers in very low yield. To synthesize the acrylate polymer, the acrylate monomer having 4-alkyloxy-4'-hydroxybip henyl (m = 2, 6) was polymerized followed by the esterification of the hydroxy group using cinnamoyl chloride. All synthesized polymers havi ng mesogenic moieties showed liquid-crystalline phases in the high tem perature range between 140 degrees C and 245 degrees C. The difference of aggregation of the cinnamoyl biphenyl mesogen among the polymers w as studied by UV-VIS spectroscopy at various temperatures. The photore action was performed in both solution and thin film. The [2+2] cycload dition reaction preferentially occurred in the thin film although both [2+2] cycloaddition and photo-Fries reactions could occur in the solu tion.