Homo- and co-polymerization of methyl methacrylate with ethylene by novel Ziegler-Natta-type Nickel Catalysts based on N,O-nitro-substituted chelate ligands

New Nickel (II) catalytic systems based on N,O chelate ligands, activated by methylaluminoxane, have been checked in the homopolymn. of Me methacrylate (MMA) and its copolymn. with ethylene. In particular, the bis(8-hydroxy-5-nitro-quinolate)nickel(II)/methylaluminoxane system as well as the catalysts obtained by oxidative addn. of either 8-hydroxy-5-nitro-quinoline or 8-hydroxy-5,7-dinitro-quinoline or 4-nitro-2-(p-nitrobenzylideneamino)-phenol to Ni(cod)2, subsequently activated by methylaluminoxane, have been employed. The influence of the reaction parameters on the catalytic activity and the characteristics of the resulting polymers has been investigated. All the obtained poly(Me methacrylate) samples display a largely prevailing syndiotacticity degree, high mol. wts. and a rather large polydispersity. The catalytic systems obtained through the oxidative procedure are able also to give copolymers of MMA with ethylene producing highly linear polyethylenes contg. a low amt. (1.5-2 mol%) of MMA co-units, thus affording materials with improved surface properties.