一种带肉桂酸酯基的聚酰亚胺液晶光定向材料研究

CINNAMATE_CONTAINING POLYIMIDE AND ITS FUNCTION AS LIQUID CRYSTAL PHOTOALIGNMENT LAYER

利用双酚A二胺单体(BISDA)与4,4-′(六氟异丙基)-双邻苯二甲酸酐(6FDA)的缩聚反应,制备了含有侧羟基的先驱聚合物PI-OH.通过PI-OH与肉桂酰氯的官能化反应,得到接有肉桂酸酯感光侧基的双酚A型聚酰亚胺PI-CI.用红外光谱(FTIR)、氢核磁共振(1H-NMR)分析、热分析(DSC)等方法表征了上述聚合物的结构和热性能.利用紫外-可见光谱(UV-Vis)对PI-CI的感光性能进行了研究.在线偏振紫外光辐照下,上述聚合物膜表现出二色向性.二向色性的强弱随光照能量的变化存在最大值.经线性偏振紫外光(LPUV)辐射后的PI-CI薄膜能诱导液晶盒中液晶分子发生均匀的定向沿面排列.上述实验表明,该聚酰亚胺是一类具有优良性能的潜在液晶光定向材料.

The precursor polymer PI-OH was prepared by the polyeondension of bisphenol-A diamine monomer （BISDA） and a dianhydride monomer （6FDA） in solution. Then cinnamoyl chloride was reacted with the hydroxyl- containing precursor to prepare the photosensitive polymer PI-CI with cinnamate pendant groups. The polymers were characterized by FTIR, 1^H-NMR and differential scanning calorimetry （DSC）. The photochemical properties of PI-CI were studied by using UV-Vis and FTIR. The polymer showed significant photodichroism upon UV irradiation due to the photodimerization. After processed by Linear Polarized Polymerization （LPP）, the spin-coated films of PI-CI were used as photo-alignment layers to assemble sandwich-type liquid crystal cells via a capillary action using a nematic liquid crystal 5CB. The observation by polarized microscope showed that the PI-CI photo-alignment layers had the ability to align LC molecules in a very uniform way. The photosensitive polymer PI-CI of bisphenol-A is promising for the application as photo-alignment layer for liquid crystal displays.