Block Copolymerizations of Vinyl Acetate by Combination of Conventional and Atom Transfer Radical Polymerization

Abstract

Four different methods of block copolymerization, combining atom transfer radical polymerization (ATRP) and conventional radical polymerization, were studied. The first two methods employed azo compounds containing activated halogen atoms. 2,2‘-Azobis[2-methyl-N-(2-(4-chloromethylbenzoyloxy)ethyl)propionamide] (AMCBP) was used to initiate the polymerization of vinyl acetate (VAc) at 90 °C. The resulting pVAc with a Cl terminal group (Mn = 47 900; Mw/Mn = 2.21) was subsequently used as a macroinitiator for styrene (St) to yield pVAc-b-pSt (Mn = 91 600; Mw/Mn = 1.80). In the second method, 2,2‘-azobis[2-methyl-N-(2-(2-bromoisobutyryloxy)ethyl)propionamide] (AMBEP) was first used to polymerize n-butyl acrylate (BA) at 30 °C in the presence of CuBr/tris[2-(dimethylamino)ethyl]amine (Me6-TREN). The pBA (Mn = 7500; Mw/Mn = 1.15) with the preserved central azo unit was dissolved in VAc and extended to a block copolymer (Mn = 41 800; Mw/Mn = 3.56). Alternatively, ATRP has been combined with a redox initiated syst...