A series of UV-curable nanocomposites were prepared with 3-(trimethoxysilyl) propyl methacrylate (MPS) modified nanosilica under the initiation of 2,2-dimethoxy-1,2-diphenylethan-1-one. It was found that MPS-modified nanosilica together with free MPS could form transparent nanocomposite coats. As the particle size of nanosilica increased, the photopolymerization rate, final double bond conversion, and tack-free time of nanocomposites increased while the surface roughness, glass-transition temperature, and UV absorbance of nanocomposites decreased. (c) 2005 Wiley Periodicals, Inc.