Epoxy-functionalized polystyrene/silica core-shell composite nanoparticles were prepared by the postaddition of glycidyl methacrylate (GMA) via emulsion polymerization. The outermost shell of obtained multilayered core-shell particles was made up of poly(glycidyl methacrylate) (PGMA). A semicontinuous process involving the dropwise addition of GMA was used to avoid demulsification of the emulsion system. The amount of grafted PGMA was quantified by Fourier transform infrared spectroscopy and was altered in a wide range (1-50 wt % to styrene). The binding efficiency was usually high (ca. 90%), indicating strong adhesion between the silica core and the polymer shell. There were approximately four or five original silica beads, which formed a cluster, per composite of nanoparticles whose size was about 60-70 nm. Other main factors of polymerization conditions including the amounts of sodium dodecyl sulfonate and silica are also discussed. (C) 2004 Wiley Periodicals, Inc.