Kinetics of reactions between chloride radicals from photo excited ion pair Fe³⁺ Cl^- and vinyl monomers in aqueous solution

Abstract

Using the System, Ion-pair Fe3+CI- Vinyl monomer, in aqueous. solution a new method of photo-polymerization of vinyl monomers is described. Light absorption by the photochemically active ion-pair Fe+3Cl-, leads to an electron transfer reaction involying reduction of the cation and oxidation of CI- to a free radical Cl which initiates polymerization. Kinetics of the reaction were followed by a study of the dependence of (a) light absorption fraction by the ion-pair, (b) light intensity, (c) concentration of monomer (d) initally added ferrous and (c) quantum yields with regard to ferrous production and monomer disappearance upon (i) Rate of ferrous ion production, ( ii) overall rate of polymerization and (iii) chain-length of polymer. A prima facie reaction scheme was put forward. Examination of the experimental results in the light of suggested scheme revealed that Cl radicals initiated polymerization and recombination of the active chain, endings terminated Polymerization.