ABSTARCTThe photopolymer materials of poly(vinyl cinnamate)(PVCi) and polyimides showing homeotropic liquid crystal (LC) alignment have been used to control LC alignment on these films using linearly-polarized (LP-) UV exposure, and the LC alignment mechanism including pretilt angle generation on the films has been discussed. In the case of PVCi, an important contribution of non-dimerized side chains of PVCi molecules to the LC alignment is pointed out. On the other hand, LC alignmemnt on homeotropically alignment polymer films exposed to LP-UV light is shown to be determined through the interaction of LC with alkyl branches attached to the polymer. It is also shown that the photo-alignment method using these photopolymer matrerials are very promising technique for the fabrication of some attractive LCD modes such as in-plane switching and vertically-aligned display modes, and an example of the application of the photo-alignment method to the fabrication of in-plane switching device is presented.