Optical properties of novel thermally switched PDLC films composed of a liquid crystal distributed in a thermoplastic/thermoset polymer blend

Thermosensitive polymer-dispersed liquid crystal (PDLC) films synthesized by phase separation during polymerization were obtained. The initial homogeneous mixture was composed of reactive polymer precursors, liquid crystal (LC) and a thermoplastic polymer (TP), polystyrene (PS) that allowed improving the PDLC performance. spersed LC phase was switched from an isotropic to a nematic state by decreasing temperature. By matching the refractive indices of the three components in the isotropic state, the film reversibly shifts from a transparent state to an opalescent/opaque state. Since the phenomenon is confined to the interior of the LC/TP droplets, a better reproducibility between cooling and heating steps (lack of hysteresis) was obtained. Influence of the film thickness was also studied.