Electrochemical polymerization of aniline and toluidines on a thermally prepared Pt electrode1

The polymerization of aniline (AN) and toluidines (o-toluidine (OTO)/m-toluidine (MTO)) was performed electrochemically on a Pt-coated titanium electrode in 1.0 M HCl using cyclic voltammetry. The results showed that the rate of polymerization was strongly dependent upon the type of monomer employed. The polymerization rate of these monomers on a Pt-coated electrode is in the order: AN>OTO>MTO. A kinetic expression for the autoacceleration process in the electrochemical polymerization of these aniline derivatives is expressed as v=kp]M]+k′M] in which k′, k, M] and p] are the initiation (nucleation process) rate constant, the rate constant when the polymer is deposited on the electrode, monomer concentration, and the total amount of polymer, respectively. The ratios of k′/k are 6.64×10^?6, 3.23×10^?6 and 3.15×10^?6, respectively, for AN, OTO and MTO polymerization. The polymerization rate of these aniline derivatives is reduced with agitation of the monomeric solution. The experimental results of E_1/2 for the first redox process showed that the AN–OTO or AN–MTO comonomer system generated true copolymers rather than the mixture of the corresponding homopolymers. The polymerization rates of these aniline derivatives on three different electrodes are in the order: IrO₂>RuO₂>Pt-coated electrode.