Effects of diluents and Ag nanowires on the electrical-optical properties of polymer dispersed liquid crystal films based on aromatic polyurethane acrylate

Polymer dispersed liquid crystal (PDLC) films have potential applications in many aspects due to unique electrically switching properties, and thus the films with excellent comprehensive properties are highly demanded at present. In this study, aromatic polyurethane acrylate (PUA) was used as polymer-matrix, and effect of diluents [lauryl methacrylate (LMA) and isobornyl acrylate (IBOA)] content on the electrical-optical properties of PDLC films was investigated. The results indicate that increase of PUA/LMA or decrease of LMA/IBOA weight ratio increases threshold and saturation voltages (V-th and V-sat), decreases on- and off-state transmittances (T-on and T-off) and increases contrast ratio. Under optimised PUA/LMA weight ratio of 31/19 or PUA/LMA/IBOA weight ratio of 31/15/4, the V-th and V-sat of the films first increase and then decrease with increasing Ag nanowires (NWs) content, and better overall properties are achieved at 0.05 or 0.075 wt.% Ag NWs, respectively. In order to explore essential reasons for the influence of diluents and Ag NWs on the properties of PDLC films, the relationships between film properties (V-th or V-sat, T-on, T-off, and response time) and liquid crystal (LC) droplets size were analysed emphatically, and the changes of system viscosity and anchoring force between polymer-matrix and LC droplets were also discussed.