Electrochemical Modulation of the Thickness of Polypyrrole Films by Using Different Anionic Dopants

The tailoring of key characteristics of conducting polymers (e.g., thickness, conductivity, degree of oxidation, color and morphology) is desirable for specific applications. We present results on the regulation of the thickness of polypyrrole films electrochemically grown on glassy carbon by potentiodynamic and potentiostatic techniques at circumneutral pH in the presence of selected aqueous dopant anions (i.e., I-, NO3-, Br-, Cl-, ClO4-, SO42- and F-). In this manner, a supporting electrolyte containing KI yields relatively thick and highly conductive films whereas KF produces little conductive, very thin films. Other electrosynthesis parameters (i.e., applied potential range, number of cycles, time) also play a key role. For example, one can obtain insulating films by applying potentials in the region required for overoxidation of the film.