Novel initiating system for the stereocontrolled radical polymerization of acrylamides: Alkyl bromide/rare earth metal triflate system

Abstract

A novel radical initiating system - rare-earth metal trifiate [Y(OTf) 3, Yb(OTf)3, Lu(OTf)3, Sc(OTf)3] and alkyl halide containing α-esters (ethyl 2-bromoisobutyrate and ethyl 2-bromopropionate) or α-amide (N,N-dimethyl-2-bromo-2-methylpropanamide) was used for the stereocontrolled radical polymerization of N-isopropylacrylamide (NIPAM). The Lewis acids serve a dual role as the promoter of the radical initiation and the controller of the stereospecific polymerization. The effects of the Lewis acid type and concentration, the initiator type and concentration, solvents, and temperature on the polymerization of NIPAM have been reported. The chain-end structure of the resulting polymer was determined by 1H NMR. We also extended this initiating system for the polymerization of N,N-dimethylacrylamide, styrene, n-butyl acrylate, and methyl methacrylate.