The copper-mediated atom transfer radical polymerization of methyl methacrylate (MMA) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was studied to simultaneously control the molecular weight and tacticity. The polymerization using tris[2-(dimethylamino)ethyl]amine (Me6TREN) as a ligand was performed even at -78 degrees C with a number-average molecular weight (M-n) of 13,400 and a polydispersity (weight-average molecular weight/number-average molecular weight) of 1.31, although the measured M.'s were much higher than the theoretical ones. The addition of copper(II) bromide (CuBr2) apparently affected the early stage of the polymerization; that is, the polymerization could proceed in a controlled manner under the condition of [MMA](0)/[methyl alpha-bromoisobutyrate](0)/[CuBr](0)/[CuBr2](0)/[Me6TREN](0) = 200/1/1/0.2/1.2 at -20 degrees C with an MMA/HFIP ratio of 1/4 (v/v). For the field desorption mass spectrum of (CuBr)-Br-I/Me6TREN in HFIP, there were [Cu(Me6TREN)Br](+) and [Cu(Me6TREN)OCH(CF3)(2)](+), indicating that HFIP should coordinate to the Cu-I/Me6TREN complex. The syndiotacticity of the obtained poly(methyl methacrylate)s increased with the decreasing polymerization temperature; the racemo content was 84% for -78 degrees C, 77% for -30 degrees C, 75% for -20 degrees C, and 63% for 30 degrees C. (c) 2006 Wiley Periodicals, Inc.