Anisotropic Phase Separation of Polymer and Liquid Crystal Composites on Patterned Alignment

Abstract

Since the development of polymer dispersed liquid crystal mode, the phase separation of polymer and liquid crystal composites have drawn much attention because of its potential of application to various kind of displays well as optical devices. The structures of isotropic phase separation are droplet or spinodal structures depending on mixing ratio and quenching rate. Recently, anisotropic phase separation of polymer and LC mixtures were also extensively studied owing to their different merits such as constructing microstructure and polymer network structure. We have studied the anisotropic phase separation by controlling the surface wetting properties. The surfaces are modulated by patterning the alignment layer using micro-contact printing method. The polymer and liquid crystals were separated according to surface modulation as temperature cooled down. We examined this phenomena by numerical calculation using simple 1-dimensional diffusion model of binary mixture. We studied the surface wetting driven anisotropic phase separation of polymer and liquid crystal composites through experiments and numerical calculation. Since the development of polymer dispersed liquid crystal mode, the phase separation of polymer and liquid crystal composites have drawn much attention because of its potential of various kind of display application as well as optical devices. Typically the morphologies of phase separation are droplet or spinodal decomposition depending on mixing ratio and quenching rate, which were called isotropic phase separation. By controlling the surface wetting properties, we could obtain the macroscopic and anisotropic phase separation of polymer and liquid crystal composites. In this experiments, the surfaces are modulated by patterning the alignment layer. The polymer and liquid crystals were separated according to surface modulation as temperature cooled down. We examined this phenomena with numerical calculation using simple 1-dimensinal diffusion model of binary mixture with assumption of simple surface potential. This technology can be applied to fabrication of flexible LCD and optical grating devices.