| Abstract
| - Copper-catalyzed atom transfer radical polymerization (ATRP) is one of the most robustand precise techniques for controlling radical polymerization. The very good control of molecular weights,polydispersities, functionalities, chain composition, and topologies unusual for radical systems combinedwith the application of transition metals as catalysts requires more detailed mechanistic studies andproof of the radical nature of active species. The following results are in agreement with the radicalnature of ATRP: reverse ATRP, chemoselectivities similar to those for conventional radical polymerization(effect of additives and inhibitors/scavengers, reactivity ratios, transfer coefficients), regioselectivitiessimilar to those for conventional radical polymerization (low proportion of head-to-head units and expectedstructure of both tail and head end groups), stereoselectivities (tacticities) similar to that in conventionalradical polymerization, EPR detection of X−Mtn+1 species resulting from the persistent radical effect,and confirmation of the termination by doubling molecular weights as well as cross-linking withmultifunctional initiators and inimers. In addition, it seems that, in most ATRP systems, the contributionof degenerative transfer and reversible formation of organometallic intermediates is small and a halogenatom is transferred in the concerted process rather than in a two-step process with the involvement ofradical anions.
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