| Metallocene catalysts, as excellent catalysts for the polymerization after the Ziegler-Natta catalyst, have opened up a new frontier in the area of organometallic chemistry and polymer synthesis. Thousands of articles and patents are published every year, and more in next year. It is no doubt that metallocene catalysts became prominent in a special period in the history of polymer science, a period that not only produced many new commercial polymers but also enhance our basic knowledge of organometallic chemistry, macromo- lecule chemistry and physics, polymer properties and structures as well as polymer processes.The produced polyolefins have narrow molecular weight distributions due to identical active sites of the catalyst. However, there were some serious problems, such as the unfavorable properties of mPO and the copolymerization of olefins and polar monomers. Several ways, such as using mix catalysts, dinuclearmetallocene, lanthanocene or late-transition metal catalyst, are available but far away from industrialization. To produce bimodal polyolefins which not only have excellent strength but have good processability is also an active study field in metallocene catalysts. The dinuclear complexes, which has two different active sites in one molecule, should be able to produce polymer with bimodal or broader molecular weight distributions. Recently a variety of dinuclear metallocene compounds have been prepared to examine their catalytic properties.The main research work was concluded as follows: (1) Ten dinuclear catalysts have been synthesized by the reaction of corresponding dilithiumed salts with two equivalents of CpTiCl3 in toluene, and characterized by 1H NMR, IR or MS. (2) Ethylene polymerization has been conduct in the presence of MAO, and the effects of conditions on the ethylene polymerization were studied in detail. (3) The relationship of the catalysts activity and metallocene structures were discussed. (4) The copolymerization of ethylene and styrene or MMA(methyl methacrylate) were explored.Six different ligands(Ll-L6), six homo-dinuclear metallocenes(Fl-F6). one Zr-Ti hetero-dinuclear metallocene(F9), three transitionmetal - rare earth heterodinuclear metallocene compounds (F7. F8. F10) have been have been synthesized by the reaction of corresponding dilithiiimed salts with two equivalents of CpTiCl:, in toluene. All complexes are characterized by 'H-NMR, IR, or MS.Ethylene polymerization has been conduct in the presence of MAO, and the effects of conditions on the ethylene polymerization (methyialuminoxane) were studied in detail. The polymerizatin results indicate that all the 10 metallocene complexes are high activity catalysts. The catalytic activity of dinuclear catalysts is lower than the corresponding mononuclear and homodinuclear metallocene of Ti or Zr.In the polymerizatin of F1(F2 orF3)/MAO, the catalyst activity decrease with the increase of the catalyst concentration while the molecular weight increases. The optimal temperature and molar ratio of Al/Cat are 50℃ and 1000 respectively. The catalyst activity and the molecular weight reached 2.44X 105gPE/molTi hr and 8.44X 104 for F1(2.40X 105gPE/molTi hr and 6.88X 104 for F2, 2.34 X 105gPE/molTi hr and 17.03X 104 for F3). With the Prolongation of polymerization time, the catalytic activity declined rapidly while the molecular weight increase.In the polymerizatin of F4/MAO, the catalyst activity decrease with the increase of the catalyst concentration while the molecular weight has peak value. With the increase of MAO/Cat, the activity increase while the molecular weight decrease. The catalyst activity and molecular weight are all reach a peak value with the increse of temperature. The optimal temperature and molar ratio of Al/Cat are 60℃ and 1000 respectively. With the Prolongation of polymerization time, the catalytic activity declined rapidly while the molecular weight increase. The highest catalyst activity and the molecular weight reached to 7.54 X 105gPE/molTi hr and 54.66 X 104.In the polymerizatin of F5/...
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