制备条件对梯形聚硅氧烷取向层光取向行为的影响

Effects of prepared conditions on the photo-alignment behavior of the ladder-like polysiloxane film

选用侧链含有双元光敏基团的梯形聚硅氧烷材料作为光取向材料,采用偏光显微镜(POM)及晶体旋转法,研究了梯形聚硅氧烷光取向层的制备条件,包括取向剂浓度、紫外光辐照度及光照时间对光取向层的取向行为的影响.结果表明,取向剂浓度越大,光敏基团更易于组装成垂直取向状态,进而诱导液晶分子形成垂直取向的分子排列方式.在一定的紫外光辐照度范围内可以有效地引起偶氮苯光敏基团的面内、面外异构化及再取向,有利于取向层诱导液晶分子形成平面取向的分子排列方式.紫外光光照时间的增加有利于取向层诱导液晶分子形成平面取向的分子排列方式.

Photo-alignment materials were prepared from ladder-like polysiloxane materials containing dual photo-reactive groups. The effects of solution concentration, irradiance and irradiation time on the photo-alignment behavior of the ladder-like polysiloxane film were investigated by polarized optical microscopy （POM） and the crystal rotation method. It was found that photo-reactive groups were prone to form homeotropic alignment with the increase of the solution concentration, and then it could induce liquid crystal molecules to form homeotropic alignment. The isomerization and reorientation both in and out of plane of azobenzene groups could be achieved within a suitable irradiance range, and then it was beneficial to the formation of in-plane alignment of liquid crystal molecules. Increasing the irradiation time availed the formation of in-plane alignment of liquid crystals molecules.