Effect of Molecular Weight on Liquid Crystal Photoalignment by Photosensitive Polyester Containing Thrifluoromethyl Moieties  

作　　者：费春红 彭增辉 吕凤珍 张伶莉 姚丽双 宣丽 

机构地区：[1]State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 [2]Graduate School of the Chinese Academy of Sciences, Beijing 100049

出　　处：《Chinese Physics Letters》2006年第11期3029-3032,共4页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant Nos 60277033 and 50473040, and the Science Foundation of Jilin Province under Grant Nos 20020603 and 20050520.

摘　　要：We investigate the liquid-crystal （LC） alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties （PPDA） with various molecular weights by crossed polarized optical microscopy. It is found that LC alignment behaviour changes with molecular weight of PPDA. The LC alignment on PPDA irradiated films with the highest molecular weight is homogeneous, while those with low and intermediate molecular weights are homeotropic. However, surface morphologies show weak dependence on molecular weight. The surfaces are smooth and there is no clear morphological anisotropy on these aligned films observed by an atomic force microscope. The surface energies of the irradiated films are also measured by using an indirect contact-angle method where both surface energy and its polar component, increase with increasing molecular weight. Different polar surface energies can be considered as a main reason for different alignment characteristics.We investigate the liquid-crystal （LC） alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties （PPDA） with various molecular weights by crossed polarized optical microscopy. It is found that LC alignment behaviour changes with molecular weight of PPDA. The LC alignment on PPDA irradiated films with the highest molecular weight is homogeneous, while those with low and intermediate molecular weights are homeotropic. However, surface morphologies show weak dependence on molecular weight. The surfaces are smooth and there is no clear morphological anisotropy on these aligned films observed by an atomic force microscope. The surface energies of the irradiated films are also measured by using an indirect contact-angle method where both surface energy and its polar component, increase with increasing molecular weight. Different polar surface energies can be considered as a main reason for different alignment characteristics.

关 键 词：ALIGNMENT PROPERTIES SURFACE-MORPHOLOGY FLUORINATED GROUPS BRUSHPOLYIMIDE POLYMERS FILMS ANGLE 

分 类 号：O753.2[理学—晶体学] O43[机械工程—光学工程]