Electro-Optical Characteristics and Morphology of a Bend Nematic Liquid Crystal Device Having Templated Polymer Fibrils

Abstract

We demonstrated a fast-switching liquid crystal display with bent polymer fibrils templated from a nematic host with a bend structure. The morphology of the bent polymer fibrils, formed by photopolymerizing a small amount of reactive monomer in a liquid crystal host, depends on monomer concentration, condition of photopolymerization, and applied electric field during UV exposure. At low monomer concentration and low curing voltage, the liquid crystal can be oriented into the twist or splay state at zero applied field. In contrast, high monomer concentration conveys dominance of the polymer network on the liquid crystal and damps the electro-optical properties of the liquid crystal. With the current nematic host, the condition for obtaining a stabilized bend state is using 3 wt% monomer concentration and 5 V curing voltage. The SEM images of polymer network morphology show a templating effect, where highly ordered fibers mimic the bend state of the liquid crystal (originally having a splay structure) under a small bias field. The device shows fairly fast optical response to the applied electric field because the templated polymer fibrils stabilize the bend state.