Anodic polymerization of 3,4-ethylenedioxythiophene from aqueous microemulsions

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDT) was studied in microemulsions containing polyoxyethylene-10-laurylether as a no n-ionic micellar surfactant. This allows to increase the solubility of the monomer in an aqueous solution. Thereby, the surfactant affects the transpo rt of EDT. Capacity measurements and cyclic voltammetry on bare Pt show the influence of the surfactant by adsorption on the metal, too. An adsorption on the polyethylenedioxythiophene (PEDT) surface could not be proved. Comb ined charge transfer and diffusion limitations control the electropolymeriz ation kinetics at low monomer and surfactant concentrations. Charge transfe r becomes limiting at high EDT concentrations. Apparent diffusion coefficie nts and the charge transfer coefficient of the electrochemical reaction wer e obtained from RDE experiments. The redox activity, UV/VIS spectra and sur face morphology (from SEM pictures) depend on the polymerization potential and the solution composition. Best films were obtained at low potentials in LiClO4. At high potentials overoxidation of the polymer takes place, but a n incorporation of the surfactant could not be detected. (C) 2000 Elsevier Science Ltd. AU rights reserved.