A comparison of redox processes for polypyrrole/dodecylsulfate films in aqueous and non-aqueous media

Polypyrrole/dodecylsulfate (PPy/DDS) films were synthesized in aqueous and ethanolic solutions and investigated in aqueous, ethanolic, methanolic and acetonitrile solutions by cyclic voltammetry (CV). The amounts of anions an d cations in the films before and after electrochemical treatment were dete rmined by electron probe microanalysis (EPMA); the film morphology was stud ied by scanning electron microscopy (SEM). The results prove that the mobil ity of bulky DDS- ions in PPy increases in the order: water < acetonitrile < ethanol < methanol. It was found that dopant DDS- ions can be easily remo ved from PPy matrix swollen in alcohols or acetonitrile by electrochemical reduction or by soaking in electrolyte solutions of these solvents. The inf luence of electrochemical treatment on the change of doping level in aqueou s solution is essentially less and depends on the cations in the test solut ion. Although the electroneutrality of PPy/DDS films during redox cycling i s realized mainly by movement of the cations in aqueous solution and by mov ement of the anions in organic solvents, nevertheless the participation of anions in aqueous and cations in organic solvents is also established. The redox properties of PPy/DDS are more dependent on the solvent of the test s olutions than of the synthesis solutions.