Simultaneous reverse and normal initiation in atom transfer radical polymerization

Atom transfer radical polymerization (ATRP) with concurrent reverse and normal initiation process was investigated. Bulk polymerizations of both n-butyl acrylate (BA) and styrene (St) were conducted using CuBr2 complexed with 1 equiv of tris(2-(dimethylamino)ethyl)amine (Me-6-TREN) as the catalytic system, initiated by 2,2'-azobis(isobutyronitrile) (AIBN) and an alkyl halide (RX). Polymerization of BA at 60 or 90 degreesC provided well-defined polymers with molecular weights up to 40 000 g/mol and low polydispersities (M-w/M-n < 1.10). Similar results were obtained for the polymerization of styrene at 110 degreesC. The effects of polymerization temperature and solubility were studied in order to moderate the high activity of the catalyst and the poor solubility of the Cu(Il) complex in monomers. Additionally, other parameters influencing this ATRP process are discussed.