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Voltammetric and in-situ FTIRS study of the electropolymerization of o-aminobenzoic acid at gold electrodes and graphite carbon electrodes: influence of pH on electrochemical behaviour of polymer films

M.I.Ferrahi*, A.Benyoucef, F.Huerta, M.Belbachir, E.Morallon

The electrochemical homo-polymerization of o-animobenzoic acid has been performed on gold and graphite carbon electrodes in perchloric acid aqueousmediumby cyclic scanning of the potential. Polymers are formed in all cases and the rate of polymerization is increased by the graphite carbon electrodes. The polymers formed have been characterized Voltametrically, in-situ FT-IR spectroscopy and scanning electron microscopy were combined to study the redox behavior of the oxidation products. Characteristic absorption features related with benzenoid and quinoid rings and different types of C-N bonds point to the operation of redox processes similar to those undergone by the parent compound polyaniline. In addition, it has been suggested the existence of chemical interaction between -COOH and –NH groups in the reduced state of the homopolymer studied can be suggested. The electrochemical behaviour of the polymer films of o-aminobenzoic acid sample that, on the contrary that the polyaniline, is electroactive to values of pH over 3, this is due to the presence of the group -COOH in the structure of polymer. To pH superior to 5 the polymer films dissolve quickly.