Controlled synthesis of α-olefins-based copolymers by organocobalt(III) complexes

Polyolefins, and ethylene-vinyl acetate (EVA) copolymers in particular, are highly attractive materials that are industrially synthesized by a free radical process for large range of applications from food packaging to coatings. Their production requires drastic synthesis conditions (high pressure and high temperature) and the resulting polymers are generally ill-defined. Controlling the polymerization of these unconjugated monomers remains however extremely difficult because of the lack of stabilizing group on their double bond. Moreover, the preparation of chain-end functionalized polyolefins is actually impossible under these conditions. This communication aims at reporting an efficient platform for the precision design of alpha-olefin-based copolymers through a controlled radical polymerization technique called Cobalt-Mediated Radical Polymerization (CMRP). The latter is based on the reversible deactivation of the radical chains by a cobalt complex bearing acetylacetonate (acac) ligands, which is very efficient under mild experimental conditions. The presentation will focus on three main axes: (i) the synthesis of a novel organocobalt(III) complex useful for the functionalization of the polymer chains, (ii) the preparation of various EVA architectures, (iii) the controlled copolymerization of vinyl acetate with a perfluorinated alkene, i.e. perfluorohexylethylene. The hydrolysis of the pendent esters moieties of these fluorinated copolymers paved the way to their polyvinylalcohol counterparts with a marked amphiphilicity.