Teixeira-Dias, Bruno; Aleman, C.; Estrany, F.; Azambuja, D.; Armelin, E. Electrochimica acta Vol. 56, num. 16, p. 5836-5843 DOI: 10.1016/j.electacta.2011.04.069 Data de publicació: 2011-06-30 Article en revista
Microstructures of poly(N-methylpyrrole) have been generated by direct electrochemical oxidation of
N-methylpyrrole with poly(styrenesulfonic acid) in aqueous solution, using a micelle formation mechanism with gas bubble templates. These microstructures present a “doughnut”-like morphology with diameters ranging from 20 to 100μm. Other anionic surfactants, such as camphorsulfonic acid and
β-naphthalenesulfonic acid, have been also employed, results evidencing that the morphology of the microstructures depends on the nature of the surfactant electrolytes. The dimensions, abundance and texture of the microstructures have been modulated by varying the surfactant molecules, the electrochemical technique, and the distance between the working and counter-electrode. The generated microstructures have been characterized using electrochemical techniques, Raman and infrared spectroscopies, scanning electron microscopy and atomic force microscopy. Hollow microstructures-containing films made
of poly(N-ethylpyrrole)/poly(styrenesulfonic acid), which present remarkable electroactivity and electrostability,
has been proved to interact with morphine molecules. Thus, systems based on this prominent material show a high ability to capture the drug molecules and to retain them for a long period of time.
Brillas, E.; Oliver, R.; Estrany, F.; Carrasco, J.; Vilar, J.; Morlans, J. Electrochimica acta Vol. 45, num. 24, p. 4049-4057 DOI: 10.1016/S0013-4686(00)00495-3 Data de publicació: 2000-08 Article en revista
The electrochemical behavior of 2,5-di-(-2-thienyl)-pyrrole (SNS) on Pt has been studied from a 10 mM monomer solution in 0.2 M LiClO4+ethanol or in 0.2 M LiCl+ethanol by cyclic voltammetry, chronopotentiometry and chronoamperometry. The monomer exhibits two similar consecutive oxidation processes. Uniform, adherent and electroactive films of dark-blue poly(SNS) doped with ClO4- or with Cl- are obtained at low potentials related to the first process. Reproducible film weights are found at 0.700 V versus Ag|AgCl during 360 s. The increase in transport rate of reactants by stirring the solution with a magnetic bar at 150 rpm accelerates the SNS electropolymerization, allowing to collect much more polymer weight than from the quiescent solution. The productivity of poly(SNS) doped with Cl- determined by ‘ex situ’ ultramicrogravimetry increases notably under stirring, although its percentage in Cl- is similar to that found under quiescent conditions. This is ascribed to the production of a major proportion of longer linear molecules in polymer, consistent with its higher conductivity when it is synthesized under stirring. This effect is not so clear for the poly(SNS) doped with ClO4- due to the little influence of stirring upon its productivity and conductivity. The detection of short linear oligomers in the soluble fractions of polymers in thioglycerol by mass spectrometry-fast atom bombardment allows to propose a radical polycondensation as initial electropolymerization mechanism.