Effect of p-allyloxycholesterolbenzoate on the electro-optical properties of polymer dispersed liquid crystal films

Polymer dispersed liquid crystal (PDLC) films were prepared from photo-polymerization of a p-allyloxycholesterolbenzoate (ACB)/2-hydroxyethyl methacrylate (HEMA)/liquid crystal (LC)/photoinitiator (IRG-651)/glass spacer (SP-220) mixture by ultraviolet (UV) irradiation. It was found that the contrast ratio of PDLC films was remarkable increased with the addition of ACB although ACB did not participate in polymerization. Under the condition that the UV irradiance (365.0 nm) was 15.0 mW· cm_-2, the curing temperature was 303.2 K, and the UV irradiation time was 10.0 min. When the mass fractions of ACB/HEMA/LC/IRG-651/SP-220 were 6.2%/18.5%/74.0%/0.3%/1.0%, the PDLC films with high contrast ratio and better electro-optical properties were obtained.