The Influence of the Methylene Blue Dye on the Rate and the Mechanism of the Oxidative Polymerization of Aniline

It is shown that one‐electron oxidation of aniline with methylene blue is possible only at low temperatures under UV radiation. The kinetics of aniline polymerization under the action of ammonium persulfate in the presence of catalytic amounts of methylene blue is studied. Kinetic curves are obtained by electron paramagnetic resonance (EPR) spectroscopy at various temperatures and concentrations of methylene blue. The catalytic action of the unassociated form of methylene blue and the deactivation of reactive complexes by the dye dimers are shown to compete. In the context of the obtained results the autocatalysis mechanism of oxidative polymerization is considered, which suggests the formation of complexes of aniline and polyaniline that are subject to subsequent rapid oxidation by the persulfate anion.