Liquid-Crystal-Refilled Polymer Network Templates Formed by an Orientationally Ordered Liquid Crystal

In this study, we investigated the behaviour of refilled polymer-stabilised liquid crystals. The polymer network is fabricated by introducing a bifunctional monomer into a nematic or chiral liquid crystal. Polymer networks formed through photo-polymerisation in a thermotropic liquid crystal will follow the self-organised order of the phase which they were formed in. Using the wash-out/refill technique, where a network is formed, the liquid crystal is washed out and leaves a long-range orientationally ordered network for polymerisation in the nematic phase and a helical network for the chiral nematic phase. The behaviour of the refilled LC devices is largely dominated by the interaction between the polymer network and the refilled liquid crystal.

This research is focused on the utilising different types of polymer networks, refilled with various liquid crystal phases. Different lyotropic or cholesteric liquid crystals with opposite handedness and varying pitch are refilled into a specific polymer network and the interaction between the network and liquid crystal is characterised by polarising microscopy and spectroscopy. We determined the lower pitch boundary of helical transfer which will cause the selective reflective intensity of the light to surpass the theoretical limit of 50%. The helical polymer network is insufficient to induce a twist grain boundary structure in an achiral SmA phase. Additionally, the nematic polymer network significantly enhances the alignment and orientation of a refilled lyotropic nematic phase, showing excellent dark state positions. When a helical network is formed in a helical thermotropic phase, the helicity can be transferred to the refilled lyotropic phase.