FI Catalysts: A New Family of High Performance Catalysts for Olefin Polymerization

This paper reviews a new family of olefin polymerization catalysts. The catalysts, named FI catalysts, are based on non-symmetrical phenoxyimine chelate ligands combined with group 4 transition metals and were developed using “ligand-oriented catalyst design”. FI catalysts display very high ethylene polymerization activities under mild conditions. The highest activity exhibited by a zirconium FI catalyst reached an astonishing catalyst turnover frequency (TOF) of 64,900 s –1 atm –1, which is two orders of magnitude greater than that seen with Cp2ZrCl2 under the same conditions. In addition, titanium FI catalysts with fluorinated ligands promote exceptionally high-speed, living ethylene polymerization and can produce monodisperse high molecular weight polyethylenes (Mw/Mn400,000) at 50 °C. The maximum TOF, 24,500 min –1 atm –1, is three orders of magnitude greater than those for known living ethylene polymerization catalysts. Moreover, the fluorinated FI catalysts promote stereospecific room-temperature living polymerization of propylene to provide highly syndiotactic monodisperse polypropylene (max. rr 98%). The versatility of the FI catalysts allows for the creation of new polymers which are difficult or impossible to prepare using group 4 metallocene catalysts. For example, it is possible to prepare low molecular weight (Mv∼103) polyethylene or poly(ethylene-co-propylene) with olefinic end groups, ultra-high molecular weight polyethylene or poly(ethylene-co-propylene), high molecular weight poly(1-hexene) with atactic structures including frequent regioerrors, monodisperse poly(ethylene-co-propylene) with various propylene contents, and a number of polyolefin block copolymers e.g., polyethylene-b-poly(ethylene-co-propylene), syndiotactic polypropylene-b-poly(ethylene-co-propylene), polyethylene-b-poly(ethylene-co-propylene)-b-syndiotactic polypropylene. These unique polymers are anticipated to possess novel material properties and uses.