A series of thick-coated homopolymer and block polymer brushes on spherical silicon gel have been successfully studied by combining initiator and atom transfer radical polymerization (ATRP). The silicon gel initiator was prepared by self-assemble. The homopolymer brushes of poly (methyl methacrylate) (PMMA), poly (acrylamide) (PAAM) and their diblock copolymer (PMMA/PAAM) were prepared by ATRP on the surface of a modified spherical silicon gel. The structure of the polymer was characterized by Fourier-transformed infrared and X-ray photoelectron spectroscopy (XPS). The results revealed that the first polymer layer of the surface was partly covered with the second polymer layer after block copolymerized with the second monomer. The surface morphology of the particles revealed that the particles were composed of an organic shell and an inorganic core. The organic content on the silicon gel was high. (C) 2004 Elsevier B.V. All rights reserved.