Nucleation and growth kinetics of electrodeposited sulfate-doped polypyrrole: determination of the diffusion coefficient of SO(4)(2-) in the polymeric membrane
| Autor: | J. M. Juárez-García, Carlos Andrés Galán-Vidal, Giaan Arturo Álvarez-Romero, M. Romero-Romo, Jorge Uruchurtu, Manuel Palomar-Pardavé, Luis Humberto Mendoza-Huizar, Héctor Herrera-Hernández, T. de J. Licona-Sánchez |
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| Rok vydání: | 2010 |
| Předmět: |
chemistry.chemical_classification
Materials science Diffusion Potentiometric titration Analytical chemistry Nucleation Polymer Polypyrrole Electrosynthesis Surfaces Coatings and Films chemistry.chemical_compound chemistry Chemical engineering Polymerization Electrode Materials Chemistry Physical and Theoretical Chemistry |
| Zdroj: | The journal of physical chemistry. B. 114(30) |
| ISSN: | 1520-5207 |
| Popis: | A kinetic study for the electrosynthesis of polypyrrole (Ppy) doped with SO(4)(2-) ions is presented. Ppy films were electrochemically polymerized onto a graphite-epoxy resin electrode. Experimental current density transients (j-t) were obtained for three different potentiometric behaviors: anionic, cationic, and a combination. Theoretical models were used to fit the experimental j-t data to determine the nucleation and growth processes controlling the polymer synthesis. It was encountered that, in all cases, pyrrole electropolimerization involves two concomitant processes, namely, a Ppy diffusion limited multiple 3D nucleation and growth and pyrrole electro-oxidation on the growing surface of the Ppy nuclei. SEM analysis of the electrodes surfaces reveals that Ppy deposition occurred over most of the electrode surface by multiple nucleation of hemispheres, as the theoretical model used for the analysis of the current transients required. Hemispherical particles formed the polymeric film displaying different sizes. The order for the particle size was as follows: anionicanionic-cationiccationic. These results are congruent with those obtained by theoretical analysis of the corresponding current transients. Analysis of the impedance measurements recorded on the anionic Ppy film, immersed in an aqueous solution with different sulfate ion concentrations evidenced that SO(4)(2-) ions diffuse through the Ppy film provoking a decrease of its electrical resistance and an increase of its dielectric constant. From the Warburg impedance coefficient, the sulfate coefficient of diffusion in the Ppy film was 1.38 x 10(-9) cm(2) s(-1). |
| Databáze: | OpenAIRE |
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