Large pretilt angle induced by an anhydride-terminal hyperbranched polyimide liquid crystal alignment layer

Abstract

Through the polycondensation of a four-functional amine with pyromellitic dianhydride, a hyperbranched polyimide (HPI) was synthesised in this study. The HPI was used for liquid crystal alignment layers. Wide angle X-ray diffraction measurement showed that the HPI film was amorphous. The morphology of the surface layer of film was determined by atomic force microscopy. It is novel that a larger pretilt angle, above 8°, has been achieved with the rubbed HPI alignment layers. This result was different from that in a previous report, in which only a 2.8° pretilt angle was induced by a HPI alignment film.

Keywords:

• polyimide
• hyperbranched polyimide
• pretilt angle
• alignment layer

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant No. 50973067). Funding was received from the State Key Laboratory of Polymer Materials Engineering of China (Sichuan University) and the project was sponsored by the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry, and Science (No. 20071108-18-12).