Sensitivity of the photo-crosslinkable polyimide for liquid crystal alignment

Two methods were developed for enhancing the photosensitivity of the cinnam ates-contained polyimide (PICA), One is to increase the content of cinnamat e side chain in PICA main chain and another is to blend some photosensitize r into PICA films. Our experimental results show that increasing the rate o f photo-dimerization decreases the alignment ability of the PICA films. Usi ng the molecular simulation method, we successfully describe the photoalign ment mechanism of the PICA films. It is also found that photo-induced LC al ignment ability of the PICA film could be enhanced through choosing a prope r coating solvent.