The controlled polymerization of methyl methacrylate (MMA) in bulk was initiated with p-chlorobenzenediazonium tetrafluoroborate (1) and Cu(II) or Cu(I)/Cu(II)/N,N',N",N"-pentamethyldietylene triamine (PMDETA) complex system at various temperatures (20, 60, and 90 degreesC). The proposed polymerization mechanism is based on the Meerwein-type arylation reaction followed by a reverse atom transfer radical polymerization. In this mechanism, aryl radicals formed by the reaction with I and Cu(I) and/or PMDETA initiated the polymerization of MMA. The polymerization is controlled up to a molecular weight of 46,000 at 90 degreesC. Chain extension was carried out to confirm the controlled manner of the polymerization system. In all polymerization systems, the polydispersity index and initiator efficiency ranged from 1.10-1.57 to 0.10-0.21, respectively. (C) 2003 Wiley Periodicals, Inc.