新型光取向液晶聚合物的制备及其性能表征

目前，液晶分子常规的定向方法是对涂有定向膜的基片进行摩擦，这种方法简单、方便，然而在摩擦过程中却难以避免产生机械划痕、污染或静电，影响了液晶分子取向的均匀性,光控取向方法是近年来发展起来的一种液晶定向新技术，即通过激光或偏振紫外光照射，引发基片上的聚合物薄膜发生光致聚合、光致异构或光致分解反应，产生表面的各向异性，进而诱导液晶分子取向。

Synthesis and Characterization of a Novel Photoalignment Liquid Crystalline Polymer

A kind of novel liquid crystalline oxetane monomers containing biphenyl, flexible spacer and cinnamoyl group was synthesized. The monomer was initiated to polymerize by boron trifluoride etherate and resulted in photoreactive polymer, which was highly sensitive to the LPL photochemically. The thermal properties and the mesophase structure of the polymer were investigated by DSC and thermal optical polarized microscope. Three exothermal peaks corresponding to an isotropic-nematic transition, nematic-smectic transition and smectic-crystal transition, respectively, were found on the DSC cooling curve of the polymer. Well-developed fan texture was observed by optical polarizing microscope. The polymer was spin-coated on a SiO-2 glass substrate from DMF solution, resulting in a thin film. Irradiation of a LP-UV light resulted in anisotropic cycloadditions of the cinnamon acyl groups, which caused the alignment of biphenyl groups in side chains at the same time. The differences of absorbance at different irradiation time were obtained which can be used to explain that the polymer can be applied in photoalignment layer.