| Metallocene catalyst, with high catalytic activity and possibility of tailoring the polymer properties such as the molecular weight, the molecular weight distribution(MWD) and the stereochemistry, has become a kind of excellent catalyst for olefin polymerization after the Ziegler-Natta catalyst. However, the narrow molecular weight distribution of the polymer produced by metallocene catalyst causes difficulties in industrial procedure. In order to resolve the problems, scientists used different structures of metallocene catalysts or special polymerization procedure to produce the polymers with broad or even bimodal molecular weight distribution.In this background, a new asymmetric 3-oxa-pentamethylene bridged asymmetric binuclear titanium metallocene complex{(CpTiCl2)2[C9H6(CH2)2O(CH2)2 C5H3CH3](C1)} has been synthesized, and characterized by GC-MS, 1H-NMR and element analysis. For comparing the asymmetric binuclear titanium metallocene complex with mononuclear catalysts, two mononuclear catalysts [IndTiCpCl2 (C2)& MeCpTiCpCl2(C3)] have also been synthesized. C1 and the mixture of C2&C3 have been used as catalyst precursor for ethylene polymerization with cocatalyst MAO(methyl alumin oxane). The influences of various parameters, such as the concentration of the catalyst, n(MAO)/n(Cat), temperature, reacting time and ethylene pressure, have been studied in detail. The detail results were showed as follow:For binuclear titanium metallocene system(C1/MAO), the GPC curve of polyethylene presented bimodal molecular weight distribution, and the MWD reached 11.00! The catalyst activity and the molecular weight reached as high as 7.38 ×105 gPE/(mol Cathbar) and 1.55×106, respectively. For mononuclear titanium metallocene system[(C2+C3)/MAO], the MWD of polyethylene was only 5.11, The catalyst activity and the molecular weight are 7.87 ×105 g PE/(mol Cathbar) and 6.17×105, respectively.
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