Kinetics of Polypyrrole Films Doped with Sulphate Ions Electrodeposited Over Graphite - Epoxy Resin Electrode

A kinetic study for the electrosynthesis of polypyrrole (Ppy) doped with SO4-2 ions is presented. Ppy films are electrochemically polymerized over graphite - epoxy resin electrode. Cyclic voltammetry shows a non-reversible process and the charge density increases as the number of cycles increases too. Current transients are obtained for three different potentiometric behaviors: anionic, cationic and a combination of both. Experimental data was statistically fitted to theoretical models to determine the nucleation and growth processes governing the polymer synthesis. Statistical fit suggests that the mechanism involved in the electropolymerization process is 3D nucleation limited by diffusion of the electroactive specie. The anionic-response polymer displays the lowest diffusion coefficient, while the cationic-response polymer displays the highest one. In all cases, both the active-sites number and the nucleation rate have considerably high values.