Photoalignment behaviour on polystyrene films containing chalcone moieties

A series of polystyrene derivatives containing chalcone (one of the biological compounds) side groups, poly(4-(4-vinylbenzyloxy)chalcone) (PCHAL#), where # is the molar content of chalcone using polymer modification reactions, were prepared in order to study the effect of the chalcone side groups on the liquid crystal (LC) alignment properties. The LC alignment behaviour of the polymer was investigated using photoalignment method. The LC cells made from photoirradiated PCHAL# films exhibited homogeneous planar LC alignment with an extremely low pretilt angle of approximately 0 degrees. We found that LC aligning ability of the LC cells made from photoirradiated PCHAL# films was affected by the molar content of chalcone side groups. For example, the azimuthal anchoring energy of a PCHAL100 (9x10(-6)J/m(2)) was found to be much larger than that of PCHAL18 (5x10(-7)J/m(2)). In addition the electro-optical characteristics of the LC cells fabricated with PCHAL100 films such as threshold voltage, driving voltage, and response time were as good as those fabricated from rubbed polyimide films, the most commonly used LC alignment layers.