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Keywords:

  • catalysts;
  • polyolefins;
  • Ziegler-Natta polymerization

Abstract

A series of novel vanadium(III) complexes bearing tridentate phenoxy-phosphine [O,P,O] ligands and phosphine oxide-bridged bisphenolato [O,P[DOUBLE BOND]O,O] ligands, which differ in the steric and electronic properties, have been synthesized and characterized. These complexes were characterized by Fourier transform infrared spectroscopy (FTIR) and mass spectra as well as elemental analysis. Single-crystal X-ray diffraction revealed that complexes 3c and 4e adopt an octahedral geometry around the vanadium center. In the presence of Et2AlCl as a cocatalyst, these complexes displayed high catalytic activities up to 22.8 kg PE/mmolV.h.bar for ethylene polymerization, and produced high-molecular-weight polymers. Introducing additional oxygen atom on phosphorus atom of [O,P,O] ligands has resulted in significant changes on the aspect of steric/electronic effect, which has an impact on polymerization performance. 3c and 4c/Et2AlCl catalytic systems were tolerant to elevated temperature (70 °C) and yielded unimodal polyethylenes, indicating the single-site behavior of these catalysts. By pretreating with equimolar amounts of alkylaluminums, functional α-olefin 10-undecen-1-ol can be efficiently incorporated into polyethylene chains. 10-Undecen-1-ol incorporation can easily reach 14.6 mol % under the mild conditions. Other reaction parameters that influenced the polymerization behavior, such as reaction temperature, Al/V (molar ratio), and comonomer concentration, are also examined in detail. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013