Reversible termination in nitroxide-mediated polymerization (NMP) (a), reversible termination in atom-transfer radical polymerization (ATRP) (b) and exchange mechanism in reversible addition–fragmentation transfer (RAFT) polymerization (c). Reprinted from ref. 6, R. P. Johnson, et al., Euro. Polym. J., 49, 2925–2948, Copyright 2013, with permission from Elsevier.