With support from the Organic Dynamics Program, Dr. Novak will investigate the design, preparation, and implementation of organometallic catalysts for the "living" polymerization of monomers known to yield stable, helical polymers. Specifically, new Ni(I) and Ni(II) catalysts for the polymerization of isonitriles will be investigated. Detailed mechanistic studies will be performed in an effort to provide the information necessary to modify these new catalysts for specific applications. The basic premise of Dr. Novak's study is that organometallic complexes, which possess versatile coordination spheres and oxidation states, can be used to alter the reactivity of polymer endgoups in a predictable manner and with a high degree of precision. Depending upon the requirements of the particular reaction, the organometallic species may be called upon to either activate or deactivate the polymer endgroup. Dr. Novak's study is designed to provide a means by which endgroups can be rendered unreactive toward all processes other than the desired initiation and propagation steps that lead to polymer formation. %%% The ultimate polymerization catalysts for the controlled synthesis of well-defined macromolecules are "living". Living polymerizations can be used to synthesize macromolecules with pre-determined molecular weights, narrow chain-length distributions, and defined endgroups. In addition, living systems allow the precise synthesis of "block copolymers", which offer a combination of properties unobtainable from simple polymer blends or random copolymers. Dr. Novak will utilize this approach for controlled synthesis of polyiso- nitriles, an important class of soluble polymers. In addition, the living nature of his approach will be exploited in the preparation of novel di- and tri-block copolymers, which are of interest as a new class of thermoplastic elastomers.
