Studies on the aqueous polymerization of acrylamide by the acidified potassium permanganate‐thioglycolic acid redox system

Abstract

AbstractThe polymerization of acrylamide in aqueous media, initiated by the acidified potassium permanganate/thioglycolic acid (1) redox pair was studied at 30±0,1°C in an inert atmosphere of dry and oxygen‐free nitrogen. The initial rate of polymerization was found to be proportional to nearly the first power of potassium permanganate concentration within the range of 2,0.10−3 to 6,0.10−3 moll−1. The rate was also found to be proportional to the first power of [acrylamide] in the range of 8,0.10−2 to 10,0.10−2 moll−1. The rate of polymerization appears to be independent of thioglycolic acid (1) concentration in the range of 1,0.10−2 to 1,2.10−2moll−1. At still higher concentrations, however, the amount of 1 depresses the rate and maximum conversion. An excess of sulphuric acid was found to affect the rate of polymerization to a slight extent and a deficiency of the acid makes the reaction to stop at an early stage, during the range studied. This indicates, therefore, the presence of an optimum concentration of H2SO4 for the smooth initiation of polymerization.A study on the effect of salts reveals that KCl and NH4Cl lower the initial rate of polymerization, whereas the reverse is true for MnSO4.H2O and Na2C2O4. The water‐miscible aliphatic alcohols e.g. CH3OH, C2H5OH, (CH3)2CHOH, and C4H9OH were found to depress the extent of polymerization.