Polymer-dispersed liquid crystal (PDLC) films were prepared by ultraviolet light-induced polymerization of photopolymerizable monomers in nematic liquid crystal (L C)/monomers/SiO2, nanoparticles composites, and the effect of SiO2 nanoparticles on the electro-optical properties of PDLC films was studied. The observed effect showed that by the adjustment of the SiO2 nanoparticles content, the refractive index ratio of the LC and polymer could be modulated, and the electro-optical properties of the polymer matrix/LC/SiO2 nanoparticles composites could be optimized. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1449-1453, 2009