Citrate and Oxalate radical-ion initiated vinyl polymerization in aqueous solution

Abstract

The kinetics of polymerisation of vinyl monomers in aqueous solution photo-initiated by radical ions C₂O₄^·− and HCitr^·− from ion-pairs FeC₂O₄+ and FeHCitr⁺ is described. A spectrophotometric investigation of the formulae and stabilities of the complexes and the evaluation of the equilibrium constants for their formation are briefly reported. The absorption spectra of the ion-pairs and those of similar other complexes are given. Kinetics of the polymerisation reactions was followed by studying the dependence of (1) monomer disappearance (2) ferrous ion production and (3) chain lengths of polymers on (a) the monomer concentration (b) light intensity (c) light absorption fraction of the ion-pairs etc. By a kinetic analysis of the experimental results in the light of the expressions derived on the basis of a reaction scheme it is concluded that initiation is by the radical-ions X^·− and termination is by recombination.