The Borderline between Simultaneous Reverse and Normal Initiation and Initiators for Continuous Activator Regeneration ATRP

Multiple methods for initiation and selecting catalyst concentration exist in atom transfer radical polymerization (ATRP). Among them, simultaneous reverse and normal initiation (SR&NI) ATRP and initiators for continuous activator regeneration (ICAR) ATRP are phenomenologically very similar. In both methods, thermal radical initiators are employed to reduce the catalyst in the higher oxidation state and generate CuI activator in situ. SR&NI and ICAR ATRP generally differ in the amount of catalyst used and in the rate of catalyst reduction. Commonly, SR&NI ATRP requires high catalyst loadings and a quick initial reduction of CuII, while ICAR ATRP relies on slow and continuous reduction of smaller catalyst loadings. However, these criteria might not be sufficient to universally distinguish among both techniques. This article investigates both methods through kinetic simulations and establishes a borderline kinetic criterion. If the polymerization rate depends on the rate of decomposition of the radical init...