Kinetics of living radical polymerization

Kinetic features of living radical polymerization (LRP) are surveyed by presenting theories on polymerization rate R_p and polydispersity index (PDI) and experimental investigation into individual LRP systems. A large activation rate constant k_act is a requisite for attaining low polydispersity. The k_act values determined for various LRP systems (various capping agents and polymers) are summarized. The characteristic behaviors on R_p and PDI brought about by the presence of bimolecular termination are presented for nitroxide-mediated LRP and copper-catalyzed atom transfer radical polymerization. The R_p is significantly retarded for some reversible addition-fragmentation chain transfer (RAFT) polymerizations, the cause of which has actively been debated. The cause for the retardation for the styrene/dithiobenzoate system is elucidated in this presentation. Besides the kinetics studies, a novel class of LRP, non-transition-metal (germanium and tin) catalyzed LRP, which was recently developed by the authors, is also presented.