Vinyl Polymerization. 404. Polymerization of Methyl Methacrylate Initiated with Substituted Imidazoles in an Aqueous Solution of Copper(II) Chloride

In order to study the effect of substituent groups of imidazole (Im) on the polymerization of methyl methacrylate (MMA) initiated with the system of Im compounds, copper(II) chloride, and water, polymerizations using N-ethylimidazole (N-Etlm) and 2-methylimidazole (2-MeIm) were carried out. The initiation ability for polymerization increased in the order 2-MeIm > N-Etlm > Im. The overall activation energies of polymerization initiated with N-Etlm and 2-MeIm were estimated to be 94.3 and 61.1 kJ/mol, respectively. The formation of complexes of the Cu(II) ion with substituted Im in water was confirmed by electronic spectra. Isolated complexes of [Cu(Im) 4 ]Cl 2 , [Cu(2-MeIm)2]Cl 2 , [Cu(N-EtIm) 2 ]Cl2, and [Cu(N-EtIm) 4 ]Cl 2 , instead of free imidazoles, were used for the polymerization of MMA. These complexes, except [Cu(2-MeIm) 2 ]Cl 2 , behaved as inhibitors of polymerization. This was due to the impossibility of formation of an adequate complex of MMA to initiate polymerization.