SET-LRP of N-isopropylacrylamide in the presence of chain transfer agent

Abstract

In this study, single electron transfer-living radical polymerization (SET–LRP) of N-isopropylacrylamide (NIPAM) in the presence of 2-mercaptoethylamine chain transfer agent (CTA) was carried out by Cu(0) generated in situ from the disproportionation of CuBr/2,2′-bipyridine (2,2′-bpy) in N,N-dimethylformamide (DMF) at 90 °C. Analysis of polymerization kinetics in the presence of CTA showed that the premature termination of growing polymer chains leads to retardation. The apparent rate constant of polymerization (k) decreased from 4.49 × 10−4 to 2.59 × 10−4 min−1 with increasing CTA concentration. The initiator efficiency (Ieff) and the chain transfer constant (Cs) were found to be 0.524 and 0.286, respectively. The molecular weights of poly(N-isopropylacrylamide) [poly(NIPAM)] produced were significantly higher than the predicted values, and the polydispersities were less than 1.22. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011