Synthesis and phase behaviour of a poly{2,5-bis[(p-ethoxyphenoxy) carbonyl] benzyl acrylate}-based mesogen-jacketed liquid crystalline copolymer

Abstract

Mesogen-jacketed liquid crystal polymers have attracted considerable interest in recent years. In this paper, a series of poly (PEPCS)-based mesogen-jacketed liquid crystal copolymers (MJLCPs) with a different 4-hydroxybutyl acrylate (HEA) content has been synthesised and characterised using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and polarising optical microscopy (POM). The hydroxyl groups are attached to the backbone in the PEPCS-co-HEA copolymers to facilitate further chemical crosslinking. These PEPCS-based MJLCPs show a reversible phase transition when the HEA content is lower than 30 wt%. T_g and T_i shift to lower temperatures as the HEA content increases. POM studies reveal that the PEPCS and PEPCS-co-HEA copolymers all show a transition from the nematic to isotropic phase on heating and from the isotropic to nematic phase on cooling. Below T_g , the long range orientational ordering of the mesogenic units is fixed.

Keywords:

• polymer synthesis
• liquid crystalline polymer
• phase transition
• smart polymer

Acknowledgements

This work was financially supported by project T-201006 of the Shenzhen Key Laboratory of Special Functional Materials. The authors are indebted to Professor Zhou Qifeng, Dr. Fan Xinhe and Dr Shen Zhihao of Peking University for their help.