Electro-optic properties of polystyrene particle-laden polymer-stabilized liquid crystals

Abstract

Particle-laden polymer-stabilized liquid crystal (PLPSLC) composites were studied as a means to improve the electro-optic properties of nematic liquid crystals. Polystyrene nanaparticles possesing no distinctive physical properties were chosen as nanodopants in order to investigate effects caused solely by the physical presence of nanoobjects. The threshold voltage, response times, relevant physical properties, and optical textures were characterized first for polymer-stabilized and particle-laden liquid crystals (PSLCs and PLLCs) made of target materials and then for PLPSLCs. Polymer stabilization allowed one to dramatically decrease the overall response time but at the cost of the increased threshold voltage. The particles alone appeared not to change the properties significantly. At the same time, when the particles and polymer were used together, interesting effects were observed: the threshold voltage could be reduced by up to two times in comparison to a polymer-stabilized liquid crystal (PSLC) while the advantage of the fast overall response time intrinsic to PSLCs was retained. A possible explanation for such behaviour can be a decrease in the effective polymer concentration caused by either the particle-induced distortion or particle-induced sparsening of the polymer network. Overall, the reported results help to shed light on how simple nanoparticles interact with the polymer network and liquid crystal. This knowledge can potentially aid the creation of more complex PLPSLC composites with desired properties in the future.