Metal-Free Radical Homopolymerization of Olefins and Their (Co)Polymerization with Polar Monomers.

Currently, a significant percentage of the industrial production of polyolefins and olefin-based copolymers is performed via free-radical polymerization, requiring demanding reaction conditions (i.e., high pressure and temperature) or via catalytic coordination insertion polymerization relying on the use of transition-metal catalysts. In general, these catalysts are not compatible with polar monomers, are air-sensitive and have to be used in high concentrations, which may preclude their use in specific applications. On the other hand, metal-free radical polymerization is a more robust method in terms of compatibility with air and types of monomers, with the limitation of requiring demanding reaction conditions. Nevertheless, the pursuit for strategies to synthesize olefin-based polymers under milder reaction conditions via metal-free radical polymerization is an active area in polymer science. The revision of the state of the art of such approaches is the focus of this contribution.