Reversible deactivation radical polymerization methods have evolved over the past few years and the ability to regulate molecular weight, monomer sequence and dispersity has emerged. Transition-metal-mediated methods, including atom transfer living radical polymerization (ATRP)1,2 and single electron transfer living radical polymerization (SET-LRP),3,4 remain two of the most popular and widely applied polymerization techniques. Both exploit the reversible
catalytic activation of alkyl halides initiators by Cu(I)Br or Cu(0) (in the
form of copper wire or powder) respectively to allow propagation while CuBr2 plays the role of a deactivating species. N-containing ligands solubilize the copper salts, control the catalyst activity via altering the redox potential and can promote disproportionation of Cu(I)Br under certain conditions. However, many of these ligands and complexes are susceptible to oxidation and should be kept under a dry, dark and inert atmosphere to avoid degradation, although in
most cases degradation often eventually occurs.