Atom transfer radical polymerization of methyl acrylate,methyl methacrylate and styrene in the presence of trolamine as a highly effective promoter

Transition metal-mediated atom transfer radical polymerization （ATRP） is a ＂living＂Jcontrolled radical polymerization. Recently, there has been widely increasing interest in reducing the high costs of catalyst separation and post-polymerization purification in ATRP. In this work, trolamine was found to significantly enhance the catalytical performance of CuBr]N,N,N＇,N＇-tetrakis（2-pyridylmethyl） ethyle- nediamine （CuBr/TPEN） and CuBr/tris[2-（dimethylamino） ethylamine] （CuBr/MesTREN）. With the addition of 25-fold molar amount of trolamine relative to CuBr, the catalyst loadings of CuBr/TPEN and CuBr/Me6TREN were dramatically reduced from a catalyst-to-initiator ratio of 1 to 0.01 and 0.05, respectively. The polymerizations of methyl acrylate, methyl methacrylate and styrene still showed first-order kinetics in the presence of trolamine and produced poly（methyl acrylate）, poly（methyl methacrylate） and polystyrene with molecular weights close to theoretical values and low polydispersities. These results indicate that trolamine is a highly effective and versatile promoter for ATRP and is promising for potential industrial application.

Atom transfer radical polymerization and copolymerization of isoprene catalyzed by copper bromide/2,2＇-bipyridine

ATRP, as one of the most successful controlled/‘‘living＇＇ radical polymerization techniques, has been applied to a large variety of monomers including styrenes,（meth）acrylates,（meth）acrylamides,acrylonitrile, and vinyl acetate. However, ATRP of isoprene still remains a challenge due to poor solubility of copper catalysts in isoprene and low chain propagation rate constant of the monomer. In this work,Cu Br/2,2＇-bipyridine was found to effectively mediate ATRP of isoprene at 100 °C, 130 °C, and 150 °C with ethyl 2-bromopropionate as an initiator. The polymerizations proceeded smoothly and reached 48.1%,53.3%, and 71.0% conversions, respectively, in 72 h, producing polyisoprenes with molecular weights close to theoretical values and relatively narrow distributions. A block copolymer of polystyrene-bpolyisoprene was prepared using Cu Br/2,2＇＇-bipyridine as a catalyst and polystyrene as a macroinitiator.The-1H NMR and-（13）C NMR analysis of polyisoprene indicated that the polymer had 88.8% 1,4-addition structure and 63.9% of the polymer backbone units were in trans-configuration.