Characterization of some poly(methyl methacrylate)s prepared by emulsifier‐free emulsion polymerization in presence of some organic ligands and their nickel complexes

The aqueous polymerization of methyl methacrylate (MMA) was studied using sodium bisulfite as initiator in absence and presence of tetraoxalyl urea (TOU), tetraoxalyl thiourea (TOthioU) and tetraoxalyl paraphenylene diamine (TOp‐phD). The effect of their nickel complexes on the polymerization rate has also been studied. Ligands with free carboxyl groups have a retarding effect on the polymerization reaction, while their nickel complexes have a catalytic effect. The polymers obtained in presence of nickel complexes were found to have wider molecular weight distribution than those obtained in their absence; this was deduced by thin layer chromatographic analysis in a binary mixture (benzene/methanol). The apparent energy of activation was found to be 5.83 × 10 4 J/mol, 1.87 × 10 4 J/mol, 2.11 × 10 4 J/mol, and 3.95 × 10 4 J/mol in absence and in presence of 0.5 g of Ni complex of TOp‐phD, TOthioU and TOU, respectively.