Novel photocrosslinking polymers for liquid crystal alignment

Abstract

Photocrosslinking polymers with optical anisotropy, which may be applied as the alignment layer for liquid crystal display (LCD), were synthesized through reaction between an epoxy compound and several kinds of cinnamic acids. The photocrosslinking polymer film was formed by spin-coating and then exposed to linearly polarized UV light. The optical anisotropy of the polymer film caused by the selective cycloaddition of the cinnamate groups was confirmed from the polarized UV-vis spectra. The polymer films irradiated by unpolarized UV light exhibited isotropic absorbance in the polarized UV-vis spectra, while the polymer films irradiated by the polarized UV light showed anisotropic absorbance. We also confirmed the photocrosslinking polymer film could align liquid crystal (LC). LC cell fabricated using the polymer films irradiated by linearly polarized UV showed anisotropic transmission of the polarized visible light, while the cell fabricated using the polymer films irradiated by unpolarized UV exhibited isotropic transmission.