The electrochemical co-polymerization of p-aminodiphenylamine and aniline: effect of pH

The electrochemical oxidation of p-aminodiphenylamine (4ADPA) in the presence of aniline in phosphate medium of pH ranging from 1 to 10.5 has been investigated. Mixtures of both monomers can be co-polymerized to produce electroactive poly aniline-co-4ADPA (Pan-4adpa) films if the pH of the medium is kept, approximately, within 3 and 9 and the upper potential limit is lower than the oxidation potential of aniline. Pan-4adpa growth rates are pH dependent and are also affected by the amount of polymeric material deposited on the electrode surface. It has been suggested the existence of a certain inhibition effect of both H+ and OH− on the polymerization reaction. Contrary to what is observed for those films synthesized at pH 5 and 7, the growth of Pan-4adpa at pH 8 seems to be an autocatalytic process until the inhibition of the polymerization reaction takes place.