Investigation Of Metallocene-titanium And Nonmetallocene-chromium For Olefin Polymerization

In this dissertation, two series of Metallocene-Titanium and Nonmetallocene-chromium catalysts were designed, synthesized and characterized by NMR and X-Ray. Olefin polymerization by these catalysts has been investigated, and conclusions were summaried as follows:(1) Design and synthesis of metallocene-titanium complexes bearing bidentate phenoxy-phosphinoyl ligands. Under MMAO, these catalysts displayed good temperature tolerance for ethylene polymerization. The catalytic activity was strongly influenced by the steric hindrance of the substituent.Catalytic activity, comonomer incorporation, and properties of the resultant polymers can be controlled over a wide range by tuning catalyst structures and reaction parameters.(2) Design and synthesis of nonmetallocene-chromium catalyst systems based on tridentate β-enaminoketonato ligands. Three of these complexes were further confirmed by X-ray crystallographic analysis. These catalysts displayed high catalytic activity towards ethylene polymerization and produce low molecular weight polyethylenes with a double bond at the end of the polymer chains.