Optical Properties of Colloid Liquid Crystal Composites

Abstract

Colloid-liquid crystal composites are a recently discovered class of soft solid comprising a dense dispersion of spherical colloidal particles in a liquid crystalline host with unusual mechanical properties. We applied this class of system to a variety of liquid crystal device modes such as twist nematic, homogenous aligned, White-Taylor GH and reflective cholesteric devices. The observed electro-optical response suggests that the local viscosity (controlling molecular reorientation) is decoupled from the (much higher) bulk viscosity. Over a wide range of particle concentrations across the full temperature range of the nematic phase, strong electro-optical switching is observed for 5CB and several of the commercially available liquid crystal mixtures. Contrast ratio, viewing angle characteristics, switching time and optical hysteresis exhibit a significant dependencies on particle density. We also demonstrate that how morphologies of the liquid crystal confined between the substrates affect the optical properties.