Ternary copolymerization photosensitive polyimide containing flexible group for liquid crystal alignment film

Ternary copolymerized polyimide (BBO-PI-OH) was successfully synthesized by copolymerization of 4,4'-oxydiphthalic anhydride (ODPA) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) with 2,2-bis (3-amino-4-hydroxyphenyl) propane (BAP). Using BBO-PI-OH as raw materials, a novel photosensitive polyimide (BBO-PI-CA) was synthesized by esterification with cinnamate chloride. BBO-PI-CA films show great transmittance in visible region (400-700 nm) and the transmittance at 400 nm is 84.67%. It can induce parallel alignment of liquid crystals (LCs) with the pretilt angle at 0.3 degrees after irradiated by non-polarized ultraviolet light (NPUVL) for 10 min. Its alignment performance remains unchanged after 8 h at 120 degrees C. BBO-PI-CA displays excellent solubility and thermal properties, which initial thermal decomposition temperature (T-d(5)) is 344 degrees C.