Mechanism of the polymerization of acrylamide initiated by the glycerol/Ce(IV) redox system

Abstract

The mechanism of the polymerization of acrylamide in aqueous medium initiated by the glycerol (R)/Ce(IV) redox system was studied. The rate of monomer disappearance was found to be directly proportional to [M]^3/2, and R^½ at lower concentrations of Ce(IV). The rate of the disappearance of ceric ions was found to be inversely proportional to [M] and directly proportional to [Ce(IV)] and [R]. Consistent with the findings of earlier investigations, a complex formation between monomer, acrylamide, and ceric ion is indicated. The experimental results show the termination to be mutual. On the basis of these and other kinetic results, an appropriate mechanism is proposed. At higher concentration of Ce(IV), a different mechanism seems to operate. The rates of disappearance of both the monomer and ceric ions are retarded on addition of anions like HSO₄⁻, SO₄⁻⁻, or ClO₄⁻, but they are accelerated on the addition of Mn(II) ions. Interpretations of the above observations are furnished.