Surface-confined atom transfer radical polymerization was used to prepare gold nanoparticle-poly(methyl methacrylate) core-shell particles at elevated temperature. First, gold nanoparticles were prepared by the one-pot borohydride reduction of tetrachloroaurate in the presence of 11-mereapto-1-undecanol (MUD). MUD-capped gold nanoparticles were then exchanged with 3-mereaptopropyltrime-thoxysilane (MPS) to prepare a self-assembled monolayer (SAM) of MPS on the gold nanoparticle surfaces and subsequently hydrolyzed with hydrochloric acid. The extent of exchange of MUD with MPS was determined by NMR. The resulting crosslinked silica-primer layer stabilized the SAM of MPS and was allowed to react with the initiator [(chloromethyl)phenylethyl] trimethoxysilane. Atom transfer radical polymerization was conducted on the Cl-terminated gold nanoparticles with the CuCl/2,2'-bipyridyl catalyst system at elevated temperature. The rates of polymerization with the initiator-modified gold nanoparticles exhibited first-order kinetics with respect to the monomer, and the number-average molecular weight of the cleaved graft polymer increased linearly with the monomer conversion. The presence of the polymer on the gold nanoparticle surface was identified by Fourier transform infrared spectroscopy and transmission electron microscopy. (c) 2005 Wiley Periodicals, Inc.