A novel Ziegler-Natta polymerization activator has been created at Northwestern University. Tris (b-perfluoronapthyl) borane (PNB) cocatalyzes Group 4 metal complexes into a powerful a-olefin polymerization system. PNB promotes efficient ethylene polymerization with a variety of Zr and Ti Ziegler-Natta catalysts. Abstract ADVANTAGE PNB promotes both monomeric and dimeric catalyst species generated in Ziegler-Natta ethylene polymerizations. Unlike previous Lewis acid borane promoters, PNB maintains high catalyst activity under a range of polymerization conditions with anticipated greater yield and productivity. SUMMARY A synthesis of tris (b-perfluoronapthyl) borane activator has been developed. The activator-catalyst complexes generated are stoichiometrically controlled, isolable and fully characterized. The MePNB- anion formed is weakly coordinating and significantly enhances overall catalyst efficiency. The powerful Lewis acid promoter readily converts Zr and Ti Ziegler-Natta complexes into highly active a-olefin polymerization catalysts. PNB exhibits the unique property to promote reactivity of both monomeric and dimeric species generated during reaction. For example bis (dimethylcyclopentadienyl) zirconium dimethyl and PBN (1/1) promote ethylene (1 atm) polymerization with an activity of 9.6 x 106 (g/mole-atm-hr) at 25°C. Similarly the dimer complex (2/1) polymerizes ethylene at 7.1 x 106 (g/mole-atm-hr). Excellent reactivity is observed with PNB and other Zr and Ti polymerization catalysts.
|State||Published - Oct 21 2003|