The reverse atom transfer radical polymerization of methyl methacrylate was investigated in different solvents: xylene, N,N-dimethylformamide, and pyridine. The polymerizations were uncontrolled, using 2,2 '-bipyridine as a ligand in xylene and pyridine because the catalyst (CuBr2/2,2 '-bipyricline complex) had poor solubility in the xylene system. In the pyridine system, the solubility of the catalyst increased, but the solvent could complex with CuBr2, which influenced the control of the polymerization. hi the N,N-dimethylformamide system, the catalyst could be dissolved in the solvent completely, but the -N(CH3)(2) group in N,N-dimethylformamide could also complex with CUBr2, SO the polymerization Could not be well controlled. The ligand of 4,4 '-di(5-nonyl)-2,2 '-bipyridine was also investigated in xylene; the introduction of the -CH(C4H9)(2) group enabled the CuBr2/4,4 '-di(5nonyl)-2,2 '-bipyridine complex to easily dissolve in xylene, and the polymerizations were well controlled. The number-average molecular weight increased linearly with the monomer conversion from 4280 to 14,700. During the whole polymerization, the polydispersities were quite low (1.07-1.10). (c) 2007 Wiley Periodicals.