A NEW MODEL FOR ELECTROCHEMICAL OXIDATION OF POLYPYRROLE UNDER CONFORMATIONAL RELAXATION CONTROL

The electrochemical behaviour of conducting polymers was modelled using a conformational relaxation treatment, defined as a rearrangement of the chain conformations along the polarization time. After relaxation other electrochemical processes are controlled and completed under diffusion control. The relaxation process is quantified by a relaxation time, which depends on the anodic overpotential (oxidation level) and the cathodic overpotential (closure and compaction of the structure related to the neutral state). Under these conditions and assuming nucleation-like kinetics for the advance of the oxidation front, anodic chronoamperograms for polypyrrole films in 0.1 M LlClO(4) + propylene carbonate solutions obtained by applying potential steps from different positive potentials to several negative values were simulated and fitted to experimental results.