Synthesis of well‐defined syndiotactic poly(methyl methacrylate) with low‐temperature atom transfer radical polymerization in fluoroalcohol

Abstract

Abstract 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 (Me 6 TREN) as a ligand was performed even at −78°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 n 's were much higher than the theoretical ones. The addition of copper(II) bromide (CuBr 2 ) 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 α‐bromoisobutyrate] 0 /[CuBr] 0 /[CuBr 2 ] 0 /[Me 6 TREN] 0 = 200/1/1/0.2/1.2 at −20°C with an MMA/HFIP ratio of 1/4 (v/v). For the field desorption mass spectrum of Cu I Br/Me 6 TREN in HFIP, there were [Cu(Me 6 TREN)Br] + and [Cu(Me 6 TREN)OCH(CF 3 ) 2 ] + , indicating that HFIP should coordinate to the Cu I /Me 6 TREN complex. The syndiotacticity of the obtained poly(methyl methacrylate)s increased with the decreasing polymerization temperature; the racemo content was 84% for −78°C, 77% for −30°C, 75% for −20°C, and 63% for 30°C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1436–1446, 2006