聚酰亚胺的侧链结构对液晶取向性能的影响

Effect of Side Chain Structure of Polyimides on Liquid Crystal Alignment

聚酰亚胺取向膜是液晶显示器的重要组成部分,对显示器件性能具有重要影响。通过实验室自行合成的两种不同侧链的二胺单体,与4,4'-二胺基二苯甲烷和均苯四羧酸二酐聚合得到含有酯键型侧链和含有醚键型侧链结构的两种聚酰亚胺。通过偏光显微镜观察,液晶分子在两种聚酰亚胺取向膜上都获得了均匀取向。测试了不同侧链结构的聚酰亚胺取向膜产生的预倾角,发现含有酯键型侧链结构的聚酰亚胺比含有醚键型侧链结构的聚酰亚胺产生的预倾角略大,且取向稳定性更好。

Polyimide alignment layer is one of the key materials of manufacturing LCD,having an important effect on the character of LCD.In this paper,the polyimides with ester group side chain and ether group side chain were synthesized from 4CAB/MDA/PMDA and 4AB/MDA/PMDA.The LC molecule alignment ability and pretilt angle induced by polyimide alignment films were studied by means of polarized optical microscope and pretilt angle tester.Moreover,the stabilities of LC alignment were investigated by heating the LC cells under 120 ℃ for 4 h.The results show that both two kinds of polyimide films can induce uniform alignment after rubbing.It was found that the polyimide with ester group side chain could induce larger angle and more stable alignment of LC than which with ether group side chain,due to the higher rigidity and thermal stability of ester group.