CONTROLLED PERMEABILITY OF FUNCTIONALIZED POLYPYRROLE FILMS BY USE OF DIFFERENT ELECTROLYTE ANION SIZES IN THE ELECTROPOLYMERIZATION STEP

A series of electrodes modified by polypyrrole films substituted by a tris-bipyridine ruthenium complex was prepared in CH3CN in the presence of a large variety of electrolytes having different anion sizes. A further exchange of the former incorporated anion with perchlorate associated with the electrochemical destruction of the conductivity of the polypyrrole backbone leads to modified electrodes exhibiting different behaviours toward the permeation of solutes like ferrocene and decamethylferrocene chosen as models. Utilization of toluenesulphonate or substituted toluenesulphonate with a long aliphatic chain as the supporting electrolyte in the polymerization media enhances markedly the permeability of the films with regard to modified electrodes prepared in a perchlorate electrolyte. In contrast, the incorporation of larger anions like anthraquinonesulphonate or naphthalenesulphonate increases the permeation of the films very little as a consequence of a lower ordered polymeric structure. The influence of other parameters such as the electropolymerization method and cross-linking degree of the polymer was also investigated.