COMPARATIVE KINETIC-STUDIES OF POLYPYRROLE ELECTROGENERATION FROM ACETONITRILE SOLUTIONS

The formation and growth of polypyrrole films on platinum electrodes from acetonitrile media has been followed by microgravimetric ex situ determination of the polymer grafted on the electrode. Kinetic parameters were also obtained from the charge consumed during polymerization. The electrogenerated polymer films were checked in the background electrolyte by voltammetry and chronoamperometry. Assuming a constant oxidation or reduction charge per unit of polymer weight, these charges were used to obtain the reaction order during the polymerization processes. The kinetics were found to be dependent on [pyrrole]0.5 [LiClO4]0.5 from gravimetric determination; [pyrrole]0.4 [LiClO4]0.5 from the polymerization charge; [pyrrole]0.4 [LiClO4]0.5 from the anodic charge of the control voltammograms and [pyrrole]0.4 [LiClO4]0.4 from the anodic and cathodic charge of the control chronoamperograms. Good agreement was found between the different methods. The good agreement between order dependence was due to the low water content.