Controlled Synthesis of Hyperbranched Polymers by TEMPO-Mediated Radical Polymerization

Abstract

Branched polymers with tunable branching densities are prepared by TEMPO-mediated radical polymerization. Thus, styrene is copolymerized with 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO methacrylate) by using 2,2'-azobis(2-methylpropionitrile) (AIBN) as initiator at 125 degrees C. The method is based on the use of TEMPO methacrylate as branching unit that possessing a nitroxyl stable radical moiety as propagation radical trap and a polymerizable methacrylate group. Depending on the concentration of TEMPO methacrylate and polymerization time, hyperbranched polymers with different branching densities are obtained.