Metal-Catalyzed Diene and Olefin Polymerizations: Mechanistic Studies and Catalyst Design

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The Chemical Catalysis Program supports the efforts of Professor Maurice S. Brookhart of the University of North Carolina at Chapel Hill focused on the design and mechanistic studies of metal-catalyzed diene and olefin polymerizations. The copolymerization of ethylene and polar vinyl monomers is under investigation. These reactions provide high molecular weight materials at high rates by employing bulky monodentate ligands that circumvent catalyst deactivation. The second effort examines the development of late metal catalysts for the polymerization of norbornene and functionalized norbornenes. The molecular weights can be controlled and living polymerizations allow co- and block polymers to be made. The third aim centers on the development of a new family of well-defined diene and olefin polymerization catalysts based on cobalt, a late transition metal that has seen little development with respect to olefin polymerization reactions. As a final part of the project, the activation of alkanes will be investigated. Electrophilic activation of alkanes is thought to proceed through alkane complexes as intermediates. As part of this work, Professor Brookhart focuses on synthesizing stable complexes of methane and higher alkanes and exploring their structures, dynamics, and reactivities with the aim of providing fundamental information useful in developing alkane functionalization reactions.Polyolefins, polydienes and related copolymers such as those produced here are central to the polymer industry and are produced on a staggering scale of over 180 billion pounds per year due to the attractive physical properties of the polymers and elastomers and the ready availability of their starting materials. The reactions in this study investigate new (cheaper) metal catalysts that provide faster rates and fewer unwanted by-products. Alkane functionalization (the final aim of the project) is a critical reaction for alternative energy production. These reactions allow methane, a gas, to be converted to methanol, a liquid fuel that is easier to store, transport, and handle. Professor Brookhart has made a serious commitment to mentoring minority students working with Project SEED and UNC-sponsored programs such as the Saturday Academy. The group contributes to the development of science programs at the Morehead Planetarium and Science Center, specifically "Today's Chemistry, Tomorrow's Fuels." Several patents have been issued based on this work and the technology has been licensed by DuPont.