Study on selective reflection properties of chiral nematic liquid crystalline composites with a non‐uniform pitch distribution

Abstract

The preparation is reported of particles of photopolymerisable monomer/chiral dopant composites with a crystalline (Cr)‐chiral nematic (N*) phase transition. By mixing particles with different pitches of the N* phase in the Cr phase and crosslinking the liquid crystal (LC) monomer molecules by photopolymerisation in the planarly oriented N* phase, an N*‐LC composite film with a non‐uniform pitch distribution was obtained. Experimental results show that the bandwidth of the reflection spectrum and the location of reflection band of the composite films can be controlled accurately by controlling the pitch lengths of the N* phase of the particles. Effects of polymerisation temperature and UV intensity on the non‐uniform pitch distribution of N*‐LC composite films were investigated.

Keywords:

• non‐uniform pitch distribution
• chiral nematic composite
• photopolymerisation
• selective reflection

Acknowledgements

Financial support from the National Science Foundation under Grant No. 20674005, National High Technology “863” Program of the People's Republic of China under Grant No. 2006AA03Z108, and Doctoral Fund of Ministry of Education of the People' Republic of China under Grant No. 20050425850.