Iniferter concept and living radical polymerization

Iniferters are initiators that induce radical polymerization that proceeds via initiation, propagation, primary radical termination, and transfer to i nitiator. Because bimolecular termination and other transfer reactions are negligible, these polymerizations are performed by the insertion of the mon omer molecules into the iniferter bond, leading to polymers with two inifer ter fragments at the chain ends. The use of well-designed iniferters would give polymers or oligomers bearing controlled end groups. If the end groups of the polymers obtained by a suitable iniferter serve further as a polyme ric iniferter, these polymerizations proceed by a living radical polymeriza tion mechanism in a homogeneous system. In these cases, the iniferters (C-S bond) are considered a dormant species of the initiating and propagating r adicals. In this article, I describe the history, ideas, and some character istics of iniferters and living radical polymerization with some iniferters that contain dithiocarbamate groups as photoiniferters and several compoun ds as thermal iniferters. From the viewpoint of controlled polymer synthesi s, iniferters can be classified into several types: thermal or photoinifert ers; monomeric, polymeric, or gel iniferters; monofunctional, difunctional, trifunctional, or polyfunctional iniferters; monomer or macromonomer inife rters; and so forth. These lead to the synthesis of various monofunctional, telechelic, block, graft, star, and crosslinked polymers. The relations be tween this work and other recent studies are discussed. (C) 2000 John Wiley & Sons, Inc.