Fundamentals of supported catalysts for atom transfer radical polymerization (ATRP) and application of an immobilized/soluble hybrid catalyst system to ATRP

A series of hybrid catalysts, comprising a tethered ligand immobilized catalyst operating in conjunction with a small amount of soluble catalyst, were evaluated for atom transfer radical polymerization (ATRP). The level of control over the ATRP of vinyl monomers was significantly improved by the addition of part per million levels of a soluble catalyst, or soluble catalyst precursor, to the immobilized catalyst. Use of a hybrid catalyst system for polymerization of vinyl monomers such as MMA, MA, and styrene provided polymers with a predetermined molecular weight and a narrow molecular weight distribution. The immobilized catalyst can be removed from the polymerization by simple filtration, or sedimentation, affording a colorless transparent polymer solution with a salient reduction in the concentration of any residual transition metal in the final polymeric products.