Reversible-deactivation radical polymerization in which the dormant species is a stable (persistent) radical and the deactivation step involves reversible fragmentation.

Notes:

1. In some cases, the dormant polymer may undergo reversible coupling.
2. Initialization usually involves decomposition of an initiator in the presence of monomer and the reagent. Polymerization commences when there is complete consumption of the mediator by initiator-derived radicals.

Examples: Mediators that are proposed to provide control by this mechanism are certain 1,1-diarylethylenes, so-called captodative monomers, and carbonothioyl compounds. This mechanism could also contribute to the degree of control observed in RAFT polymerization.