In this study, polydimethylsiloxane (PDMS)/ polyacrylate composite polymer latex was synthesized via polymerization of the acrylate monomer in the presence of vinyl-containing PDMS seeded latex. The polymerization was initiated by (CO)-C-60 gamma-ray irradiation. The morphology of the PDMS/polyacrylate composite polymer latex was a core-shell structure with PDMS as the core and polyacrylate as the shell. There was an interpenetration layer between the PDMS core and the polyacrylate shell. The composition of the vinyl-containing PDMS and the PDMS/polyacrylate composite latex were investigated with NMR and Fourier transform infrared spectroscopy, respectively. The effect of irradiation dose on the seeded emulsion polymerization conversion is discussed. Finally, the mechanical properties of latex film, such as water-absorption ratio, tensile strength, pendulum hardness, and heat-decomposed temperature, were tested. The results showed that the mechanical properties of the PDMS/polyacrylate film were remarkably improved when compared to the polyacrylate film. (C) 2003 Wiley Periodicals, Inc.