Polymerization of styrene with tetradentate chelated α-diimine nickel(II) complexes/MAO catalyst systems: Catalytic behavior and microstructure of polystyrene

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• 作者：Lidong Li^a ; Clara S.B. Gomes^a ; Patr&#xed ; cia S. Lopes^a ; Pedro T. Gomes ; ^a ; ^{pedro.t.gomes@ist.utl.pt" rel="nofollow} ; Herm&#xed ; nio P. Diogo^a ; José ; R. Ascenso^a
• 关键词：α ; -diimine ligand ; Late transition metal ; Microstructure ; Nickel complex ; Polyolefin ; Polystyrene
• 刊名：European Polymer Journal
• 出版年：2011
• 出版时间：August 2011
• 年：2011
• 卷：47
• 期：8
• 页码：1636-1645
• 全文大小：438 K

文摘

The recently reported N,N,N,N-tetradentate chelated α-diimine Ni(II) complexes 1–3 were demonstrated to be efficient precatalysts for the polymerization of styrene in the presence of MAO, producing isotactic-enriched heterotactic polystyrenes (isotactic contents in the range 73–75.5%). The corresponding sequence distributions were determined by NMR spectroscopy, and fitted to six probabilistic models of chain propagation. A better conformity to a Bovey–first order Markov chain propagation model was obtained, indicating a chain-end control mechanism. A comparison of the microstructural features with other polystyrenes obtained by several different types of initiation indicates that the polystyrenes are formed by a coordination insertion polymerization mechanism at the nickel centers.