Relation between Overall Rate of ATRP and Rates of Activation of Dormant Species

Abstract

The rate of atom transfer radical polymerization (ATRP) depends on the rate constant of propagation (kp) and concentration of growing radicals. The latter is related to the ATRP equilibrium constant (KATRP) and concentrations of alkyl halides, activators, and deactivators. Activation of alkyl halides by CuI/L and deactivation of radicals by X–CuII/L are vital processes providing good control in ATRP. Rates of these reactions are typically identical throughout polymerization, since the ATRP equilibrium is maintained in essentially all ATRP systems. There are new ATRP processes carried out with ppm of Cu catalysts, such as activators regenerated by electron transfer (ARGET), initiators for continuous activator regeneration (ICAR), supplemental activators and reducing agents (SARA), and electrochemically or photochemically mediated ATRP (eATRP, photoATRP). In these processes, as in conventional radical polymerization (or in RAFT), concentration of radicals is established by balancing rates of radical generat...