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Keywords:

  • catalysts;
  • polyolefins;
  • Ziegler–Natta polymerization

Abstract

A new titanium complex [PhN=C(Ph)CHC(CF3)O]2TiCl2 (2a), with an asymmetric β-enaminoketonato [N,O] ligand, has been synthesized and fully characterized. With modified methylaluminoxane as a cocatalyst, the behaviors of ethylene polymerization, and ethylene/α-olefin and ethylene/norbornene copolymerization have been explored in detail. Relative to its regioisomer 2b ([PhN=C(CF3)CHC(Ph)O]2TiCl2), the present catalyst exhibits significant predominance. The catalytic activity in 2a-catalyzed homo- and copolymerization are much higher than those in 2b-catalyzed (co)polymerization. Furthermore, compared with 2b, catalyst 2a possesses an obviously stronger ability towards copolymerization, due to a wide coordination space caused by exchanging the position of the phenyl group and trifluoromethyl group on the framework.