Cobalt‐Mediated Radical Polymerization

Abstract

Controlled radical polymerization driven by cobalt complexes has emerged over the past decades as a powerful tool for the design of precision polymers. This so‐called Cobalt‐Mediated Radical Polymerization (CMRP) relies on the temporary deactivation of the radical chains by a cobalt complex, which strongly decreases the probability of bimolecular termination reactions. CMRP imparts control to industrially important monomers and allows formation of polymers with predictable molecular weights and well‐defined architectures. This book chapter describes general mechanistic principles, key parameters and synthetic progress of CMRP as well as remaining challenges.

Impact of Catalyzed Radical Termination (CRT) and Reductive Radical Termination (RRT) in Metal‐Mediated Radical Polymerization Processes

“…There is also a strong interest in iron‐based ATRP catalysts (Fe II /Fe III ), because of the low cost and toxicity of this element . The dominating element in OMRP, on the other hand, is cobalt …”

Oxygen‐Triggered Switchable Polymerization for the One‐Pot Synthesis of CO2‐Based Block Copolymers from Monomer Mixtures

“…[13] Relative to CoÀOb onds,C o ÀCb onds are less polar and tend to break homolytically,w hich is key to various enzymatic reactions mediated by vitamin B 12 . [14] Cobalt complexes have allowed the well-controlled organometallic-mediated radical polymerization (OMRP) of challenging nonconjugated monomers,such as vinyl acetate (VAc), [15] vinyl chloride, [16] N-vinyl amides, [17] and vinylidene fluoride (VDF) [18] (Scheme 1b). In particular,the radical polymerization of VA cwas shown to be well-controlled also when mediated by the (Salen)Co II system through ad egenerative transfer mechanism with AIBN initiation at 60 8 8C, leading to the generation of (Salen)Co III À PVAc as ad ormant species.…”

An efficient, heterogeneous, reusable atom transfer radical polymerization catalyst

“…[14][15][16] Several approaches have been used to eliminate the current drawbacks, such as electrochemical, 17 photochemical methods [18][19][20][21][22][23][24][25][26] or using very low concentrations of copper salts. [27][28][29][30][31] Moreover, apart from Cu(I), other metal salts like cobalt, 32 iron etc. 33 have also been used as alternative solutions.…”