Metal-Centered Radicals and Organometallic Complexes in Controlled Radical Polymerizations of Olefins

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Dr. Bradford B. Wayland, Chemistry Department, University of Pennsylvania, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division for the study of metal-centered radicals and organometallic complexes in the controlled radical polymerizations of olefins. Low spin cobalt(II) metal-centered radicals are highly effective in the catalytic chain transfer that controls molecular weight and introduces end group alkene functionality during radical polymerization. Consequently, kinetic-mechanistic studies of catalytic chain transfer by low spin cobalt(II) metalloradicals and the measurement of organo-cobalt and other organo-metal bond dissociation thermodynamics will be undertaken. Organo-cobalt porphyrin complexes mediate a highly precise living radical polymerization of acrylate monomers to form low polydispersity homo-polymers and block copolymers. Hence, the mechanism of this polymerization process will be studied, the scope of organo-metallic species that catalyze the polymerization will be evaluated, and the factors that promote and inhibit radical interchange during the polymerization will be determined. The living radical polymerization method will be exploited to prepare new classes of functionalized polymeric materials.Polyolefins are important commercial products. This research will develop a rational approach to the synthesis of various polyolefins and potentially result in new structurally defined block copolymers with unexplored material properties. Students involved in the study will learn not only sophisticated methods involving inorganic and organic chemistry, but will be introduced to major issues and challenges in energy-related research, polymer chemistry, catalysis and materials science.