Living Aqueous Microemulsion Polymerization of Ethylene with Robust Ni(II) Phosphinophenolato Catalysts
Fei Lin, Tobias O. Morgen, Stefan Mecking
Abstract
Due to chain transfer events being competitive with chain growth, ethylene polymerization by P,O-chelated Ni(II) complexes usually affords low molecular weight polymers or oligomers. We now show that appropriately bulky substituted phosphinophenolato Ni(II) can polymerize in a living fashion, virtually devoid of chain transfer. Aqueous polymerizations with microemulsions of [κ2-P,O-2-(2-(2′,6′-(MeO)2C6H3)C6H4)(Ph)P-6-(3′,5′-(CF3)2C6H3)C6H3O-NiMe(pyridine)] (3) at 30 °C yield polyethylenes with narrow molecular weight distributions (Mw/Mn 1.02 to 1.34) and ultrahigh molecular weights (up to 2 × 106) in the form of aqueous nanoparticle dispersions. Catalyst stability and activity are maintained up to 70 °C in water.