Photo-reactive polymer films for rubbing-free alignment of liquid crystals

点击翻译按钮获取中文摘要

It was demonstrated that linearly polarized light irradiation of films of polymers with azobenzene side chains determines the uniaxial orientation of nematic liquid crystals (LCs). In this fiscal year, the followings have been revealed.1. Benzylidenephthalimidines (BPI) having a skeleton related to stilbenes display E/Z photoisomerization and [2+2] photodimerization. It was confirmed that both photochemical reactions take place in thin films of polymethacrylates with BPI side chains. The thermal stability of homogeneous alignment of LCs induced by the photoirradiated films was influenced by the level of photocrosslinkage.2. It was observed that slantwise irradiation of films of azobenzene polymers results in the emergence of dichroism even though actinic light is not linearly polarized. The orientational direction of azobenzene chromophores was determined by the direction of light incidence. This technique using slantwise photoirradiation generated pretilt angles of LCs, demonstrating that rubbing-free production process of LC-aligning films is available solely by a photochemical way.