Ethylene polymerization by bis(salicylaldiminate)nickel(II)/aluminoxane catalysts (pages 2534–2542)
Carlo Carlini, Alessandro Macinai, Francesco Masi, Anna Maria Raspolli Galletti, Roberto Santi, Glauco Sbrana and Anna Sommazzi
Article first published online: 7 APR 2004 | DOI: 10.1002/pola.20102
The homopolymerization of ethylene by using different catalytic systems based on dinitro-substituted bis(salicylaldiminate)nickel(II) precursors such as bis[3,5-dinitro-N(2,6-diisopropylphenyl)]nickel(II) (XI) and bis[3,5-dinitro-N(phenyl)]nickel(II) (X) in combination with organoaluminum compounds was investigated. In particular, the catalytic performances were studied as a function of the main reaction parameters, such as temperature, pressure, Al/Ni molar ratio, and duration. Methylaluminoxane resulted in the best co-catalyst. Activities up to 200 kg polyethylene/(mol Ni × h) to give a linear high-molecular-weight polymer were achieved. The influence of the bulkiness of the substituents on the N-aryl group of the aldimine ligand was also checked; it resulted in a determinant for catalytic activity rather than for polymer characteristics.