Electric and Electro-Optic Investigations on Polymer Dispersed Liquid Crystal Films

Abstract

We obtained polymer-nematic liquid crystal composite films by the solvent induced phase separation (SIPS) method. We used a novel polymer obtained by the synthesis of a macromolecular structure with a matrix basis of methyl methachrylate and a chromophore group with extended conjugation (MMA + I) and the nematic liquid crystal E3 (BDH). We studied the electro-optical effects using He–Ne lasers of two different intensities, for a.c. driving fields of different frequencies and voltages. At low frequencies, the emergent optical signal is modulated in amplitude, doubling the frequency of the a.c. driving field. At higher intensities of the incident laser beam, the variation of the transmission with the a.c. driving electric field is much smaller. In the KHz frequency range, the decrease of the fluctuations of the transmitted light intensity with the increase of the frequency was observed. We also plotted the volt-ampere (V-I) characteristics of the polymer/LC composite films in different coordinates systems in order to determine the contribution of the nonlinear effects to the electric conduction.