Effect of the skeleton structures in the side chain of polyimides on their film surface properties and pretilt angles of liquid crystal molecules

Abstract

Polyimides (1c–4c, 1c'–4c') with side chains (1–4) containing four different skeletons were synthesised and characterised. Results showed that a similar high side chain abundance took place on the surface of the films, which was independent of the skeleton structures, while the pretilt angles of liquid crystal molecules were considerably affected by the skeleton structures. 1c, 1c' and 2c, 2c' achieved vertical alignment while 3c, 3c' and 4c, 4c' only obtained low pretilt angles. The main reason, based on surface testing results and molecular modelling, was the different interactions between liquid crystal molecules and the skeletons in the side chains.

Keywords:

• liquid crystal
• polyimides
• pretilt angle
• side chain

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 50433010 and 50773044) and the Doctoral Fund of Ministry of Education of China (No.20040610028).