Polymer dispersed liquid crystals for large area switchable windows: Effect of liquid crystal loading

Polymer dispersed liquid crystals are composite materials which have been proposed in the last years as large area electrically switchable windows. Their electro-optical performance is strictly related to the morphology of liquid crystal droplets. We have investigated the morphological and electro-optical properties of droplets of nematic liquid crystals dispersed in NOA65 polymer matrix. We found that droplets size and dispersion become larger and larger as the liquid crystal loading is increased. At higher concentrations of liquid crystal two different distribution of droplet size are recognised. Switching fields and haze in the ON state show a minimum value when the liquid polymer/crystal weight ratio is around 55:45 for which the best performance is achieved.