Synthesis Of Coumarin-Containing Side-chain Liquid Crystal Polymers And Studies Of The Property Of Photochemistry

The liquid crystalline polymers with photosensitive groups can self-assemblelike the low-molar-mass liquid crystals. Also when the polymer film is exposed tolinearly polarized (LP) light, it can react a polarization-axis selective photoreaction,Upon irradiating, a small negative optical anisotropy results from an axis-selectivephotoreaction of the photosensitive groups, while annealing in the LC temperaturerange leads a large positive optical anisotropic change of the polymer film .Photo-alignment in polymeric film is a promising technique applicable to thephotoalignment layer of liquid crystal displays, birefringent optical devices, andholographic data storage devices.In this study，three monomers with photosensitive group and a monomercontaining nothing but a mesogenic unit were synthesized . Four homopolymersand three copolymers were obtained by polymerization. The photosensitivegroups of coumain and cinnamate are photo-cross-linkable. All the structureswere confined by FT-IR and1HNMR spectra. Their thermal Properties weremeasured by DSC and POM, and results indicated that three monomers, onehomopolymer and all the copolymers could form liquid crystalline phase.The photoalignment performance of the synthesized polymers was testedpreliminarily. The results indicate that the photoinduced optical anisotropy Aincrease with the exposure dose increase, and then became stable quickly,though A∥and A⊥continued increasing. What’s more, the photoinduced opticalanisotropy A was thermally enhanced after annealing. The stability ofcoumain-containing polymers was better than cinnamate-containing polymers,because the former polymer materials only undergo an [2+2] photo-cross-linkingreaction.