Side-chain cholesteric liquid crystalline elastomers containing isosorbide as chiral agent – synthesis and characterisation

Abstract

In this work the new-style nematic monomer M₁ , chiral crosslinking reagent M_C and a series of new side-chain cholesteric liquid crystalline elastomers derived from M₁ and M_C were prepared. The effect of the content of the chiral crosslinking unit on phase behaviour of the elastomers has been discussed. Polymer P₁ showed nematic phase, P₂ –P₇ showed cholesteric phase, P₃ formed Grandjean texture in the heating cycle and turned out a blue Grandjean texture in the cooling cycle, P₂ –P₃ with less than 6 mol% of chiral crosslinking agent gave rise to selective reflection. The elastomers containing less than 15 mol% of the crosslinking units displayed elasticity, reversible phase transition and high thermal stability. Experimental results demonstrated that the glass transition temperatures reduced first and then increased, and the isotropisation temperatures and the mesophase temperature ranges decreased with increasing content of crosslinking unit.

Keywords:

• Grandjean blue texture
• chiral
• crosslinking reagent
• elastomers

Acknowledgments

The authors are grateful to the National Natural Science Fundamental Committee of China and HI-Tech Research and Development Program (863) of China, to the China Postdoctoral Science Foundation, and Postdoctoral Science and Research Foundation of Northeastern University for financial support of this work, and to Shen Yang Scientific and Technical Bureau Foundation.