Aqueous redox polymerization of acrylamide initiated by citric acid/permanganate

Abstract

Abstract The homogeneous redox polymerization of acrylamide by the citric acid/permanganate initiating system was investigated at 35±0,2°C under nitrogen. Variation of the activator concentration in the range of 2,5.10 −3 to 20,0.10 −3 mol/dm 3 had no effect on the rate of polymerization. The initial rate increased with the increasing catalyst concentration and a value of nearly unity of the catalyst exponent confirmed a unimolecular chain termination process. The rate varied linearly with the monomer concentration over a wide range (5,0.10 −2 to 20,0.10 −2 mol/dm 3 ). The initial rate increased with the increasing temperature but the maximum conversion showed a decrease as the temperature was raised above 35°C. The energy of activation, in the temperature range of 25 to 45°C, was found to be 55,90kJ/mol (13,36 kcal/mol). The addition of neutral salts, Co(NO 3 ) 2 , Ni(NO 3 ) 2 , organic solvents, and complexing agents, all water soluble, reduced the rate and percentage of conversion. The introduction of MnSO 4 or of more catalyst (at intermediate stages) into the system increased both the rate and limiting conversion.