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Different catalyst samples of nickel(II) and copper(II) phthalocyanines supported over bentonite clay (Indian type) were prepared with complex loadings ranging between 0.2 and 2.2 wt.‐%. Catalyst activities were investigated in the bulk polymerization of methyl methacrylate (MMA) at 80°C in the absence and in the presence of sodium bisulfite as a cocatalyst. In all cases, the catalyst efficiency was evaluated in terms of conversion yield (%), polydispersity index (M̄w/M̄n) was determined via GPC analysis in toluene. The stereotacticity was determined from 1H NMR spectra. Optimum polymerization conditions were determined for both catalyst systems. Samples with metal phthalocyanines loadings of 1.8% were the most active ones. The polymers produced have controlled molecular weights, which are nearly proportional to conversion, show narrow molecular weight distributions and syndiotactic‐rich steric structures. Nickel phthalocyanine seemed to have more stereoregulating effect while copper phthalocyanine had a more enhancing effect for the living polymerization process. The microstructure of solid catalysts was investigated by means of scanning electron microscopy and were correlated with activity data.

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