COBALT-MEDIATED FREE-RADICAL POLYMERIZATION OF ACRYLIC-MONOMERS

The use of square-planar low-spin cobalt complexes to control the free-radical polymerization of vinyl monomers is described. The control exerted depends on both the catalyst and the monomer structure. Monomers with a beta-hydrogen (for example, methacrylates) undergo catalytic chain transfer, which is a powerful synthetic technique for producing macromonomers. Monomers without a beta-hydrogen (for example, acrylates) are capable of pseudo-living polymerization by exploitation of the 'persistent radical' effect. The structure of the cobalt complex is shown to be very important in determining its catalytic activity