AN ELECTROCHEMICAL QUARTZ-CRYSTAL MICROBALANCE-BASED INVESTIGATION OFTHE PROPERTIES DISPLAYED BY ELECTROACTIVE POLYPYRIDINE FILMS

The properties of poly-2,5-pyridine films, deposited on gold electrode s through a nickel-catalyzed cathodic polymerization route carried out in acetonitrile, were re-investigated by electrochemical quartz cryst al microgravimetry in conjunction with cyclic voltammetry and coulomet ry. Special attention was paid to the ion transport during film reduct ion and ion binding of the polymer characterized by both electroactive and coordinative properties. The suitability of the electrochemical q uartz crystal microbalance for the study of chemically modified electr ode surfaces results in reliable information pointing out that polymer ic chains in the framework are characterized by the presence of bipyri dyl moieties grafted upon one another by coordinating nickel(II) ions whose coordination shell was identified. Moreover, the nickel-doped po lymer turned out to undergo two cathodic processes both leading to the polymer changing from the insulating to the conductive state. The for mer is due to the reduction of coordinated nickel ions and is accompan ied by the release of the counter anions originally present, while the uptake of cations from the supporting electrolyte is accompanied with reduction by the injection of electrons into the polymer backbone. Th e program developed for the simultaneous acquisition of experimental d ata and their processing is described.