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Appl. Sci. 2014, 4(2), 195-206; doi:10.3390/app4020195
Article

Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

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Received: 31 October 2013; in revised form: 10 March 2014 / Accepted: 17 April 2014 / Published: 29 April 2014
(This article belongs to the Special Issue Polymer Electrolyte Membrane (PEM) Fuel Cells)
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Abstract: Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM+BF4 and phenyltrimethylammonium chloride or TMPA+Cl) were studied by X-ray photoelectron spectroscopy (XPS), contact angle, differential scanning calorimetry (DSC) and impedance spectroscopy (IS) measurements performed with dry samples after 24 h in contact with the IL-cations BMIM+ and TMPA+. IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS) seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM+ membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM+ on the transport of H+ across wet Nafion/BMIM+ doped membranes.
Keywords: Nafion; ionic liquids; XPS; impedance spectroscopy; contact angle; hydrophobic character Nafion; ionic liquids; XPS; impedance spectroscopy; contact angle; hydrophobic character
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

del Valle Martínez de Yuso, M.; Arango-Díaz, A.; Bijani, S.; Romero, V.; Benavente, J.; Rodríguez-Castellón, E. Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations. Appl. Sci. 2014, 4, 195-206.

AMA Style

del Valle Martínez de Yuso M, Arango-Díaz A, Bijani S, Romero V, Benavente J, Rodríguez-Castellón E. Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations. Applied Sciences. 2014; 4(2):195-206.

Chicago/Turabian Style

del Valle Martínez de Yuso, María; Arango-Díaz, Ana; Bijani, Shanti; Romero, Virgina; Benavente, Juana; Rodríguez-Castellón, Enrique. 2014. "Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations." Appl. Sci. 4, no. 2: 195-206.

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