Controls of solubility parameter and crosslinking density in polyurethane acrylate based holographic polymer dispersed liquid crystal

The effect of solubility parameter mismatch between liquid crystal (LC) and resin, and crosslinking density of resin phase on morphology and diffraction efficiency of holographic polymer dispersed liquid crystal (HPDLC) have seen systematically studied by varing the chemical structure of polyurethane acrylate resin with regard to the prepolymer molecular weight, type of diisocyanate, and functionality of reactive diluent. It has been found that with dissimilar chemical structure leading to large difference in solubility parameter between LC and resin, and with high crosslinking density under similar solubility parameter difference, fast formation of grating, large droplet size and high diffraction efficiency were generally obtained.