Alignment behavior of liquid-crystal molecules on the surface of photoreactive polymer films treated by uv-irradiation and rubbing

Abstract

Photoreactive polyimides, which contain cinnamoyl and 4-fluorocinnamoyl moieties as side groups, were synthesized, providing a good quality of films. For these polymers in thin Rims, the photoreactivity and photoreaction-induced polymer alignment were examined by polarized and unpolarized uv-exposures and uv-visible spectroscopy. And, their rubbing processability was investigated. The alignment and pretilt of LCs on the film were dependent upon all the process parameters (polarization, exposure dose, and exposing method of uv light and rubbing density) as well as the fluoro substituent.