Ethylene Polymerization Using Zirconocenes Supported On Pentafluorophenyl-Modified Solid Polymethylaluminoxane

Three permethylindenyl zirconocenes have been supported on a hexane-insoluble form of polymethylaluminoxane modified with 40 wt % pentafluorophenol (sMAO(PFP)). The solid precatalysts were characterized by solid-state nuclear magnetic resonance spectroscopy, and their ethylene polymerization activity was studied. When supported on sMAO(PFP), (SB)-S-Me2(Cp,I*)ZrX2 ({(eta(5)-C9Me6)Me2Si(eta(5)-C5H4)}ZrX2; X = Cl, CH2Ph, and Me) showed ethylene polymerization activities up to 25% higher than when supported on unmodified sMAO with the same [Al](0)/[Zr](0) catalyst loading: activities of 6454 and 5144 kg(PE) mol(Zr)(-1) h(-1) bar(-1) at 80 degrees C for (SB)-S-ME2(Cp,I*)ZrCl2 supported on sMAO(PFP) and sMAO, respectively. The systems produced relatively low-molecular weight polyethylenes (M-w < 170 kg mol(-1) at 80 degrees C) with minimal defects and branching. The polymers showed good flowability, although they displayed more aggregated morphologies than polyethylenes produced from unmodified sMAO. On increasing the solvent volume fivefold, the activity and polymer molecular weights approximately doubled.