Voltammetric study of poly(o-toluidine)

M. J. RODRÍGUEZ PRESA; M. I. FLORIT; G. IBARRA; C. MOINA ; D. POSADAS

Seattle

Congreso; 196th Meeting of the Electrochemical Society; 1999

Electrochemical Society

The reduction and relaxation of Poly(o-toluidine) (POT) was studied as a function of the wait time at different waiting potentials near the reduction potential of the polymer. Also, the influence of the film thickness, the acid concentration, and the ionic strength of the external electrolytic solution on these processes was studied. Two types of electrolytes were employed: perchloric acid and sulphuric acid. Both the reduction and the relaxation times depend on the proton concentration of the external electrolyte media and on the film thickness. They are independent on the ionic strength, and, on a limited range, on the waiting potential. The voltammetric response of fuly reduced and relaxed polymers shows that, at low sweep rates, the kinetics is controlled by slow ionic movements within the polymer. Experiments with medium exchange show that: once the polymer is fully reduced and relaxed, its state is independent of the composition and concentration of the electrolyte, in which this particular state was obtained. Furthermore, they also show that the shape of the voltmmetric oxidation profile depends exclusively on the composition and concentration of the electrolyte in which the polymer is being oxidized. This means that the effect of the solution composition and concentration manifests only through the participation of protons and anions in the mechanism of oxidation of the polymer.