Effect of chemical structures of polyimides on photosensitivity of liquid crystal alignment using a polarized UV exposure

Unidirectional liquid crystal (LC) alignment produced by polarized UV exposure was examined using polyimides (PIs) synthesized using different diamines. The dichroic ratio of the resulting LC cells suggests that the UV photosensitivity is primarily controlled by the chemical structures of the PIs used. The UV absorption and fluorescence spectra of the PI films, and molecular conformations of the diamines, indicate that the photosensitivity is controlled by the UV absorption efficiencies and molecular conformations of the PIs.