Synthese, Characterization And Catalysis Behavior Towards Polymerization Of Nickel Complexes Bearing Two β-Ketoiminato Chelate Ligands

In this dissertation, a series of non-metallocene complexes based on transition metals nickel had been synthesized and characterized, and the activities of these complexes as catalysts for olefin polymerization were investigated. Conclusions were summarized as follows:1. A series of nickel(â…¡) complexes bearing two nonsymmetric bidentate -ketoiminato chelate ligands have been prepared, and characterized by means of 1H NMR, 13C NMR. Two structures of complexes have been confirmed by X-ray crystallographic analysis.2. These nickel (â…¡) complexes were investigated as catalysts for the vinylic polymerization of norbornene in presence of modified methylaluminoxane (MMAO) as a cocatalyst. These nickel(â…¡) complexes display high activities of up to 1. 16 104 kg/mol -h and produce high molecular weight polymers of up to 870 kg/mol. Catalytic activity and the viscosity-average molecular can be controlled over a wide range by the variation of the reaction parameters such as Al/Ni molar ratio, norbornene/catalyst molar ratio, monomer concentration, reaction temperature and time.3. These nickel(â…¡) complexes activated with MMAO are also capable of catalyzing the polymerization of methly methacrylate (MMA), producing high molecular weight and syndiotatic-rich PMMAs.