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Cationic [TiCl6]+2 and anionic [TiCl6-xLx]-(2-x) titanium complexes with crown ether as pre-catalyst for ethylene polymerization
A series of ionic complexes of composition [M. Crown]+ [TiCl5]-, where M - Li, Na, K; Crown - dibenzo-18-Crown-6, benzo-15-crown-5, dibenzo-24-crown-8 has been synthesized by the interaction of alkali metal chlorides, titanium tetrachloride and crown ethers in anhydrous toluene. Carrying out these syntheses in acetonitrile results in crystallization of complexes solvated with acetonitrile. The structure of three complexes was determined by X-ray diffraction. In the presence of an activator – {Et2AlCl+Bu2Mg}, the complexes catalyze the polymerization of ethylene with a productivity of up to 4500 kg PE/mol Ti h atm. The resulting ultra-high molecular weight polyethylene (Mv in the range 1.4 – 2.8*106 Da) can be processed by a solventless method into high-strength (up to 2.1 GPa) and high-modulus (up to 118 GPa) oriented films.