| The synthesis and characterization of several classes of macromolecules, including inorganic dendrimers, hyperbranched oligomers of ethylene, high molecular weight, linear polymers of ethylene, and linear α-olefins is described.; The synthesis of hyperbranched macromolecules consisting of either a borosiloxane or phosphosiloxane backbone, each with pendant phenyl groups has been achieved. These macromolecules are prepared by reaction of either boric or phosphoric acid with a phenylchlorosilane. These compounds are interesting as potential precursors to glass and ceramic materials. Under mild conditions, these macromolecules can be pyrolyzed to form glassy or ceramic materials. This reaction occurs by cleaving of either the boron-phenyl or siliconphenyl bond to form a material which consists of entirely -B-O-Si-O- or -P(O)-O-Si-O-repeat units.; By preparing low molecular weight polymers of ethylene with high levels of branching, viscous liquid oligomers have been obtained. The catalyst system described here consists of a late transition metal complex of either Ni or Pd and a Lewis acid, which, when exposed to ethylene, leads to the formation of liquid oligomer with a unique microstructure previously undescribed.; A transition metal-free catalyst system useful for the synthesis of polymers of ethylene and propylene has been discovered. Since the first reports of the preparation of polymers of ethylene and propylene in the 1950's, several catalyst systems have been reported, resulting in the belief that the transition metal was a vital catalyst component if indeed high molecular weight polymer is to be obtained. Our experiments indicate that trace metal impurities are not responsible for the polymerization activity seen. The catalyst systems described here consist of an aluminum alkyl and an organo-Lewis acid. Thermal analysis indicates that these polymers are highly linear, with melting points near 140°C, and the narrow polydispersities observed suggest a “single site” catalyst system.; A multi-component catalyst system useful for the preparation of linear α-olefins has been described. The system described here consists of an alkoxide complex of Ti, an aluminum alkyl, an alkyl zinc, and Ni acetyl acetonate. The addition of zinc and nickel complexes to these systems leads to increased activity, as well as to greater selectivity of linear over branched product. |
