Advanced macromolecular engineering via cobalt-mediated radical polymerization of ethylene, α-olefins and other less activated monomers

Designing well-defined polymers made of ‘Less Activated Monomers’ (LAMs) via reversible deactivation radical polymerization (RDRP) has long been a challenge due to the lack of radical stabilizing group on the double bond of these monomers. In the last years, substantial progress has been achieved for controlling the radical polymerization of these monomers including ethylene and α-olefins via cobalt-mediated radical (co)polymerization (CMRP). This technique relies on the reversible deactivation of the radical chains by cobalt complexes in order to limit the extent of irreversible termination reactions. This communication aims at reporting recent advances in the CMRP of LAMs and the synthesis of unprecedented functional macromolecular structures resulting therefrom.
For example, α,ω-functional ethylene/vinyl acetate (EVA) copolymers were prepared via radical polymerization using bis(acetylacetonato)cobalt(II) as mediator. Subsequent ring-closure of such difunctional precursors via copper-catalyzed Huisgen dipolar cycloaddition also gave access to EVA macrocycles and to their EVOH-counterparts after hydrolysis. Furthermore, the sequential CMRP of ethylene and LAMs leading to unique poly(ethylene)-containing block copolymers will be presented for the first time. Finally, the versatility of CMRP will be illustrated by the synthesis of well-defined polymer architectures based on fluorinated α-olefins and N-vinylamides.