Study of PDCLC Materials Using Fabry Perot Scattering Technique

Abstract

Polymer dispersed cholesteric liquid crystals (PDCLCs) consist of liquid crystal (nematic and Cholesteric) droplets that are dispersed in a solid polymer matrix. PDCLCs are a relatively new class of materials that hold promise for many applications ranging from switchable windows to projection displays. These materials, which are simply a combined application of polymers and liquid crystals, are the focus of extensive research in the display industry. Cholesteric liquid crystasls are often considered to exhibit a modified nematic phase, the molecules they contain being parallel, but characterized by a continual rotation of the direction of molecular alignment (Director). This unusual twisting often causes the appearance of bright colors when cholesteric liquid crystals diffract light [1]. The mixtures of PDCLCs with room temperature nematic liquiod crystal TL205 doped with Cholesteryl materials having different liquid crystal concentrations and polymer PN393 were investigated. The concentration of cholesteric liquid crystal played crucial role in the properties of PDCLCs. The phase transition temperatures (PTTs) of the samples thus prepared were studied using Fabry Parol scattering studies (FPSS), Optical Polarising Microscope (OPM) and Differential Thermal Analysis (DTA).