Kinetics of controlled radical polymerization

Controlled radical polymerization (CRP) is based on the reversible activation of a dormant species P-X to a polymer radical P* by thermal, photochemical and/or chemical stimuli. In the presence of a monomer, P* will transiently propagate until it is deactivated back to P-X. If the number of activation-deactivation cycles is large enough, and if the [P*]/[P-X]<10^-5, then all the chains will slowly propagate with nearly equal rates, living very little chance for termination and other side reactions, at least in limited ranges of polymerization time and chain length. This process leads to polymers with a low polydispersity and a low fraction of dead chains. The activation processes and polymerization rates of various variants of CRP are discussed.