Ceric ion-initiated polymerization of acrylonitrile in the presence of polyols

Abstract

The polymerization of acrylonitrile was studied in aqueous sulfuric acid with the redox initiator system, ceric ammonium sulfate/glycerol at 15-25°C. The initiation was effected by the ceric ion and the radical produced from the reaction of Ce⁴⁺ with glycerol. At lower concentrations of Ce⁴⁺, the rate of monomer disappearance was proportional to [M]^1,5, [G]^0,5, and [Ce⁴⁺]^0,5, and the rate of ceric ion disappearance was directly proportional to [Ce⁴⁺] and [G]. The results were explained by a kinetic scheme involving the oxidation of substrate by Ce⁴⁺ to give the primary radical and further reaction of the latter with Ce⁴⁺ to give the final product, and initiation of polymerization both by Ce⁴⁺ and the primary radical. The initiation by Ce⁴⁺ was found to be negligible as compared to that by the primary radical. The termination step is postulated to be mutual at lower concentrations of Ce⁴⁺ and linear at higher concentrations of Ce⁴⁺. The induction period and the rate of polymerization was compared with those of other polyol systems, such as sorbitol and mannitol.