Ceric ion-reducing agent redox initiated vinyl polymerisation

Abstract

Ceric perchlorate/formaldehyde (F)redox couple initiated polymerisation of the monomer methyl acrylate (MA), acrylonitrile (AN), and methyl methacrylate (MMA) in perchloric acid (25°C) was carried out. The rate of polymerisation was directly proportional to [M]² and [F] for all the systems. The rate was independent of [Ce⁴⁺] for the systems with MA or AN, but inversely proportional to [Ce⁴⁺] with MMA as the monomer. The rate of ceric disappearance was directly proportional to [Ce⁴⁺], [F], and [M]. The results were explained by a kinetic scheme involving the oxidation of the substrate by Ce⁴⁺ to give the primary radical and further reaction of the latter with Ce⁴⁺ to give the final product, and initiation of polymerisation both by Ce⁴⁺ and the primary radical, propagation followed by termination by the metal ion. Only with MMA as the monomer, the initiation by Ce⁴⁺ was found to be negligible compared to that by primary radicals. In the system with the reducing agents t-butanol and n-butanol, there was found to be 1:1 complex formation between the substrate and Ce⁴⁺. Otherwise the scheme is similar to that proposed for the Ce⁴⁺/HCHO/HClO₄/AN (MA) systems.