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

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.