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Keywords:

  • catalysis;
  • copolymerization;
  • ethylene;
  • half-titanocene;
  • metal-organic catalysts/organometallic catalysts;
  • norbornene;
  • polyolefins;
  • titanium

ABSTRACT

Ethylene copolymerizations with norbornene (NBE) using half-titanocenes containing imidazolin-2-iminato ligands, Cp′TiCl2[1,3-R2(CHN)2C[DOUBLE BOND]N] [Cp′ = Cp (1), tBuC5H4 (2); R = tBu (a), 2,6-iPr2C6H3 (b)], have been explored in the presence of methylaluminoxane (MAO) cocatalyst. Complex 1a exhibited remarkable catalytic activity with better NBE incorporation, affording high-molecular-weight copolymers with uniform molecular weight distributions, whereas the tert-BuC5H4 analog (2a) showed low activity, and the resultant polymer prepared by the Cp-2,6-diisopropylphenyl analog (1b) possessed broad molecular weight distribution. The microstructure analysis of the poly(ethylene-co-NBE)s prepared by 1a suggests the formation of random copolymers including two and three NBE repeating units. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2575–2580