可溶性聚酰亚胺液晶取向膜的制备与性能

液晶取向膜是液晶显示器中的关键材料,为了制得性能优良的液晶取向膜,我们通过铃木偶联反应制备了3种含有不同末端基团的3,5-二氨基联苯,将制得的3种二胺单体分别与环丁烷四甲酸二酐聚合得到3种新型的聚酰亚胺。 利用核磁氢谱对单体和聚合物的结构进行了表征,测试了聚合物的溶解性、热稳定性以及用作液晶取向膜的性能。 结果表明,所得的聚酰亚胺具有良好的溶解性和热稳定性,经过机械摩擦后,末端带有甲氧基的聚酰亚胺能使液晶分子平行于摩擦方向取向,末端带有苯氧羰基和联苯氧羰基的聚酰亚胺能使液晶分子垂直于摩擦方向取向。 此类可溶性的聚酰亚胺液晶取向膜将简化制备工艺并在柔性显示器件中具有较大的应用价值。

Preparation and Properties of Soluble Polyimides as the Liquid Crystal Alignment Layer

The liquid crystal alignment layer plays a critical role in the liquid crystal display. In order to prepare liquid crystal alignment layer with excellent properties, three kinds of 3,5-diaminobiphenyls with different terminal groups were synthesized by Suzuki coupling reaction, and three polyimides were prepared by polymerization of the three diamines with 1,2,3,4-cyclobutanetetracarboxylic dianhydride. The structures of monomers and polymers were characterized by proton nuclear magnetic resonance (¹H NMR) spectroscopy. The solubility, thermal stability and properties of the polymers as liquid crystal alignment layer were studied. The resulting polyimides show good solubility and thermal stability. After rubbing, the polyimide with methoxy as terminal group can align the liquid crystal molecules parallel to the rubbing direction. On the contrary, the polyimides with phenoxycarbonyl and biphenoxycarbonyl as terminal groups align the liquid crystal molecules perpendicular to the rubbing direction. This kind of soluble polyimide liquid crystal alignment film will simplify the preparation process and present great application value in flexible display devices.