A polysiloxane derivative with methacryloyloxy groups (MPS) that was obtained from the reaction of polymeric tributylstannyl ester of silicic acid and (3-methacryloyloxypropyl)dimethylchlorosilane was demonstrated to be a useful inorganic component, for the preparation of organic-inorganic hybrid resins as nanocomposites. The copolymerizations of MPS with common monomers such as styrene, acrylonitrile, and methyl methacrylate proceeded readily at room temperature under UV irradiation to give the corresponding resins in good yields. The resins obtained from MPS and methyl methacrylate showed good transparency, hardness in a scratch test, and resistance to toluene but had poor flexibility. (C) 2000 John Wiley & Sons, Inc.