Journal of Polymer Science Part A: Polymer Chemistry, Vol.48, No.2, 417-424, 2010
Copolymerization of Ethylene with 1-Hexene Promoted by Novel Multi-Chelated Non-Metallocene Complexes with Imine Bridged Imidazole Ligand
A series of novel bridged multi-chelated non-metallocene catalysts is synthesized by the treatment of N,N-imidazole, N,N-dimethylimidazole, and N,N-benzimidazole with n-BuLi, 2,6-dimethylaniline, and MCl4 (M = Ti, Zr) in THF. These catalysts are used for copolymerization of ethylene with 1-hexene after activated by methylaluminoxane (MAO). The effects of polymerization temperature, Al/M molar ratio, and pressure of monomer on ethylene copolymerization behaviors are investigated in detail. These results reveal that these catalysts are favorable for copolymerization of ethylene with 1-hexene featured high catalytic activity and high comonomer incorporation. The copolymer is characterized by C-13 NMR, WAXD, GPC, and DSC. The results confirm that the obtained copolymer features broad molecular weight distribution (MWD) about 33-35 and high 1-hexene incorporation up to 9.2 mol %, melting temperature of the copolymer depends on the content of 1-hexene incorporation within the copolymer chain and 1-hexene unit in the copolymer chain isolates by ethylene units. The homopolymer of ethylene has broader MWD with 42-46. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 417-424, 2010
Keywords:broad molecular weight distribution;copolyethylene;copolymerization;metallocene catalysts;methylaluminoxane;non-metallocene complexes;Ziegler-Natta polymerization;polyethylene