Ion exchange mechanism of polypyrrole and poly-N-methylpyrrole with toslylate as doping anion: An electrochemical quartz crystal microbalance study

Abstract

The electrochemical quartz crystal microbalance (EQCMB) was employed to investigate ion exchange processes in polypyrrole and poly-N-methylpyrrole in aqueous electrolytes. The films were deposited potentiodynamically onto gold electrodes. The insertion and expulsion of ions was monitored during the electropolymerisation and also during the redox reaction of the polymer films. It was found that the reduction of polypyrrole in 0.1 M Na-tosylate is accompanied by insertion of cations and water. On the other hand, the oxidation of poly-N-methylpyrrole in Na-tosylate solution gives rise to insertion of tosylate together with hydroxide ions. In toluenesulfonic acid solution proton expulsion is observed coupled with anion insertion. The results are discussed in view of the polymer structures. The different mass transport phenomena in polypyrrole and poly-N-methylpyrrole are interpreted by means of interactions of the anion with the polymer chains.