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Equilibrium and transport electrochemical processes in conducting polymer coated electrodes

Comparative studies for the series of background ions allowed to make a choice among the different mechanisms of the polymer doping process which can involve both cationin and anionic exchange with the solution (because of coupling between cationc and immobilised anions in the film). The solvent effect in the transport properties inside the polymer film at low charging levels have also been studied.

Kinetics of electron-transfer reactions both at the polymer/solution interface and within the bulk film (solute species) were used as a test for the contribution of the metal/polymer interface to the overall potentinal drop and to the change of the solvation of electroactive species during its transfer into the polymer phase.

The distribution of electric potential in the metal/polymer/solution system as well as the polymer semiconductor properties were studied by using the photo- and spectroelectrochemical techniques. This approach provided additional information on dark electrochemical processes in these systems. These investigations involved extensive studies of the nature, mechanism and kinetics of the photoprocesses that occurred at the polymer modified electrodes. The photoelectrochemical results were complemented by electrochemical impedance and voltammetric measurements both upon illumination and in the dark. Additional information was provided by by frequency resolved optical reflection spectroscopy. For films of polyaniline and its derivatives on plainum and glassy carbon electrodes, the role of solvent and overoxidation was anlaysed.

In a possible extension of the project these experimental studies will be tightly related to the theoretical modelling of the equilibrium structure and kinetic phenomena at the metal/polymer film interface or at the solution/film interface. The theoretical analysis will take into account the short-range interaction effects between the electronic species ion and solvent molecules inside the film as well as upper limitations for their concentrations and the polymer film structural relaxation and its swelling.

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