ORGANOMETALLIC NICKEL-CATALYSTS BOUND TO POLYMERIC MATRICES IN THE OLIGOMERIZATION AND OR POLYMERIZATION OF OLEFINS WITH A REPLICA OF THE SUPPORT MORPHOLOGY

Organometallic nickel complexes with bidentate P O chelating ligands of type Ph(PPh3)Ni(Ph2PCHCOPh) were heterogenized according to a new strategy - through the =CH- group of the ylidic ligand - and their behaviour in the polymerization and/or oligomerization of ethylene investigated. When anchored to polystyrene resins the catalytic systems showed a high and very selective activity in ethylene polymerization (1-2.5 kg of polymer (g Ni)-1 h-1) working in slurry or in gas-solid phase with reproduction of the morphology of the starting resins. When the matrix is a microspherical resin (0.1-0.3 mm diameter) the HDPE (high-density polyethylene) obtained is in the form of regular and very compact spheres of 3-7 mm diameter. Depending on the physical characteristics of the matrix (crosslinking, surface area, porosity, existence of spacing groups), compact spheres, hollow spheres ('eggs'), geminates, polymer powders, or liquid oligomers were obtained.