Liquid crystal-refilled polymer network templates formed by photo-polymerisation in an orientationally ordered liquid crystal

Abstract

Polymer networks, formed via photo-polymerisation in a thermotropic liquid crystal, will largely follow the self-organised order of the phase in which they form. Using the wash out – refill technique, where a network is formed, the liquid crystal is washed out and the network refilled with a different liquid crystal material produces devices which are largely dominated by the interaction between the polymer network and the refilled liquid crystal. We have used this technique to determine the lower pitch boundary of a chiral nematic which will allow enhancing the selective reflective intensity of light beyond the theoretical limit to approximately P ≈ 1 μm. We further demonstrate that a helical polymer network is not sufficient to induce a twist grain boundary TGB-like structure in an achiral SmA phase and provide an explanation in terms of elasticity. A third aspect of the investigations is the drastic enhancement of alignment and orientation of a refilled lyotropic nematic phase to achieve excellent dark states over large areas. Using a helical network, it is shown that helicity can be transferred to refilled lyotropic phases when a polymer network was formed in a helical thermotropic phase.