Investigation of the electro-optical behaviour of UV-cured polymer/liquid crystal systems

The electro-optical proprieties of Polymer Dispersed Liquid Crystal (PDLC) films were studied to understand the relationship between the conditions of preparation, the morphology, and the response to an external electrical field. The PDLC films were obtained by polymerization induced phase separation (PIPS) process using Ultra-violet (UV) cured system composed of a monomeric diacrylate and a nematic liquid crystal using two irradiation doses, 50 mJ/cm2 and 150 mJ/cm2. The analysis of electrooptical responses were investigated in terms of transmission vs voltage curves as a function of thickness and show similar shapes, low transmission in the off-state and high transmission in the on-state in both cases. The results obtained for 150 mJ/cm2 exhibit slightly lower switching voltages and in particular, the 50 mJ/cm2 samples lead to relatively large dispersed data in terms of threshold voltages.