Synthesis and characterization of photo-sensitive polyimide containing a chalcone structure for photo-alignment of liquid crystals

We introduced the chalcone moiety as a side chain in the backbone of polyimide for photo-alignment layers. The rate of photo-reaction was followed by the disappearance of the CCCO bond in the chalcone moiety using UV-visible spectroscopy. The decay of the absorption peak at around 340 nm decreased significantly in less than a few minutes at room temperature. The alignment properties are very much dependent on the chain length of the chalcone moiety.