Homopolymerization of n-butyl methacrylate by bis(salicylaldiminate)Cu(II)/MAO catalysts

Polymn. catalysts based on copper precursors appear particularly interesting due to the low metal cost, limited toxicity and modest sensitivity to deactivation by polar species. To date, .alpha.-olefin and polar monomer coordination polymn. catalyzed using copper catalysts has been scarcely investigated, and a good part of the literature is represented by patents. Here this research has been expanded to the study of the performances of bis(salicylaldiminate)copper(II)/methylaluminoxane (MAO) catalysts in the polymn. of Bu methacrylate. The study of the catalytic activity of bis(salicylaldiminate)copper(II)/MAO systems in Bu methacrylate polymn. was focused on the relationship between the catalytic behavior and the main reaction conditions and ligand structures. The electronic and steric characteristics of the chelate ligands play an important role in the catalytic performances. The presence of electron-withdrawing nitro groups on the chelate ligands increased the catalytic activity which reached 36 kgpolymer mol-1 h-1, the highest value up to now reported for copper systems in methacrylic or acrylic monomer polymn. These performances were ascribed to copper catalysts activated by MAO: without copper precursor, working in the presence of MAO and free salicylaldimine ligand, complete inactivity was ascertained.