Synthesis Of Phenoxy-ester Ligated Metal Complexes And Their Catalytic Properties

Ethylene propylene rubber?EPR?is widely used in automotive parts,waterproofing membrane for building materials,heat-resistant hose,wire and cable sheathing,lubricating oil additives and polyolefin modification due to excellent electrical insulation properties,excellent resistance to ozone,aging and chemical attack.With the rapid development of the construction industry and automobile industry,the demand for ethylene propylene rubber is increasing greatly and the EPR industry is moving towards a globalized model.The key for ethylene propylene copolymerization technology lies in the development of catalysts.Based on the catalyst design concept of"ligand-oriented design",and the fact of the enhanced activity of inner electron donor of ester for Z-N catalyst,we prepared a series of ligands by introduction of substituents with different space steric hindrance and electroic effect to phenoxy-ester?a kind of electron donor?matrix.The novel non-metallocene single-site catalysts--[O,O]bidentate coordination compounds were then obtained by the coordination of these ligands and transition metal.Finally catalytic activities of as-prepared catalysts for ethylene propylene copolymerization were studied.The structures of polyolefins were also characterized.Firstly,2,6-dibromo-4-methyl phenol was used as a starting material and treated with silane in the first step to prepare phenoxy silane compounds?precursors?.Then precursors were reacted with chloro-carbonic ester to obtain 6 kinds of phenoxy-ester ligands?L₁^L₆?containing different substituents.The structures of precursors and ligands were characterized using infrared spectrometer?FT-IR?,nuclear magnetic resonance and mass spectrum?MS?.Secondly,the ligands of L₁^L₆ were reacted with titanium tetrachloride respectively in the presence of n-butyl lithium in order to obtain six phenoxy-ester ligated titanium complexes of C₁^C₆.Ligand L₆ was also reacted with zirconium tetrachloride and vanadium oxychloride to obtain other phenoxy-ester ligated metal complexes.The structures of the complexes were characterized by FT-IR and MS.Finally,all complexs were used as the catalysts for ethylene propylene copolymerization together with ⁱBu₃A1/Ph₃CB?C₆F₅?₄ as the cocatalyst.It was found that as-prepared catalysts could catalyze copolymerization of ethylene and propylene.As-obtained ethylene propylene copolymers were all random copolymers.The correlation between R₁,R₂ substituents of complexes and polymerization activity,polymer molecular weight was studied.The catalytic activity of titanium complex was observed to decline with increasing the size of R₂ and with descreasing the size of R₁,whereas the copolymer with higher molecular weight was synthesized using the titanium complex with lower R₁substituent.The correlation between metal species and polymerization activity,polymer molecular weight was also investigated.The vanadium complex shows the best catalytic activity for ethylene propylene copolymerization whereas the zirconium complex exhibits the lowest catalytic activity for ethylene propylene copolymerization,titanium complex catalyzes copolymer with higher molecular weight.