Chinese Journal of Applied Chemistry ›› 2020, Vol. 37 ›› Issue (12): 1403-1410.DOI: 10.11944/j.issn.1000-0518.2020.12.200185

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

WEN Pushana*, HE Ruib, ZHAO Guangliana, LIANG Xinga, LEE Myonghoonc*   

  1. aSchool of Chemistry and Chemical Engineering,Zunyi Normal University,Zunyi,Guizhou 563006,China;
    bWuhan China Star Optoelectronics Technology Co.,Ltd.,Wuhan 430078,China;
    cGraduate School of Flexible and Printable Electronics,Jeonbuk National University,Jeonju 54896,Korea
  • Received:2020-06-15 Revised:2020-09-11 Accepted:2020-09-18 Published:2020-12-01 Online:2020-12-07
  • Contact: LEE Myonghoon, professor; Tel/Fax:+82-63-22412337; E-mail:mhlee2@jbnu.ac.kr; Research interests:synthesis and design of liquid crystal materials
    Co-corresponding author:WEN Pushan, associate professor; Tel/Fax:0851-28927159; E-mail:wenpushan@126.com; Research interests:preparation and application of functional materials
  • Supported by:
    National Natural Science Foundation of China(No.21766040), Guizhou Provincial Natural Science Foundation(No.[2016]1419), the Natural Science Research Project of Guizhou Education Department(No.[2019]058) and the Basic Science Research Program Through the National Research Foundation of Korea (NRF) funded by the Ministry of Education(No.2018R1D1A1B07044250)

Abstract: 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.

Key words: polyimide, alignment layer, solubility, thermal stability

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