Atom transfer radical polymerization of methyl methacrylate by copper(I)‐pyridine‐2‐carboximidate catalysts

Abstract

AbstractPyridine‐2‐carboximidates [methyl (1a), ethyl (1b), isopropyl (1c), cyclopentyl (1d), cyclohexyl (1e), n‐octyl (1f), and benzyl (1g)] were prepared from the reaction of 2‐cyanopyridine with the corresponding alcohols. Cyclopentyl‐substituted 1d was found to be a highly effective ligand for copper‐catalyzed atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). For example, the observed rate constant for a CuBr/1d catalytic system was found to be nearly twice as high as the cyclohexyl‐substituted CuBr/1e catalytic system [kobs = (1.19 vs 0.56) × 10−4 s−1). The effects of the solvents, temperature, catalyst/initiator, and solvent/monomer ratio on the ATRP of MMA were studied systematically for the CuBr/1d catalytic system. The optimum condition for the ATRP of MMA was found to be a 1:2:1:400 [CuBr]o/[1d]o/[ethyl 2‐bromoisobutyrate]o/[MMA]o ratio at 60 °C in veratrole solution, which yielded well‐defined poly(MMA) with a narrow molecular weight distribution of 1.14. The catalytically active copper complex 2d was isolated from the reaction of CuBr with 1d. Narrow molecular weight distributions as low as 1.06 were achieved for the CuBr/1d catalytic system by employing 10% of the deactivator CuBr2. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2747–2755, 2004