Practical synthesis of dendritic hyperbranched polymers by reversible deactivation radical polymerization

Abstract

Recent developments in the one-step synthesis of structurally controlled hyperbranched polymers by radical polymerization in terms of molecular weight, dispersity, number of branching points, branching density, and number of chain-end groups are reported. The structural character of HB-polyacrylates and HB-polystyrenes synthesized by organotellurium-mediated radical polymerization (TERP) resembles that of dendrimers and dendrons, which, although enabling complete control over branched structures, requires tedious stepwise synthesis. Successful control is realized by a new molecular design for the monomer inducing the branching structure, in which the reactivity of the dormant group changes from inactive to active upon the reaction and incorporation of the monomer into the polymer backbone. The principle of the monomer design and the scope and limitation of the polymerization method are described here. Recent developments in the one-step synthesis of structurally controlled hyperbranched polymers (HBPs) in terms of molecular weight, dispersity, number of branching points, branching density, and number of chain-end groups by radical polymerization are summarized. Copolymerization of conventional vinyl monomers and a vinyl telluride, which induces the branching structure, under organotellurium-mediated radical polymerization (TERP) affords HBPs with dendrimer and dendron structures. The same synthetic strategy under atom transfer radical polymerization is also discussed.