Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 22: Poster: Glass Transition and Dynamics of Liquids
CPP 22.9: Poster
Dienstag, 15. März 2011, 18:00–20:00, P2
Perfluorinated surfactants as model charged systems for understanding the effect of confinement on proton transport and water mobility in fuel cell membranes. A study by QENS — Sandrine Lyonnard1, Quentin Berrod1, •Beate-Annette Brüning1, Gerard Gebel1, Armel Guillermo1, Hossein Ftouni1, Jacques Ollivier2, and Bernhard Frick2 — 1CEA, INAC/SPrAM/PCI, UMR 5819, 17 Av. des Martyrs, 38000 Grenoble, France — 2Institut Laue-Langevin,6 rue Jules Horowitz,38042 Grenoble,France
We have investigated the dynamical properties of water confined in mesomorphous phases of perfluorinated sulfonic surfactants [1]. These systems mimic the physico-chemical properties of the perfluorinated Nafion membranes which are used as electrolyte in fuel cells. As the surfactants offer the advantage to self-assemble in well defined organized phases (e. g. hexagonal, lamellar), they are used as model charged systems to understand the structure transport relationship in complex real materials. Geometry and typical confinement size can be tuned through water concentration and temperature. A QENS study on hexagonal and lamellar phases was performed on both time-of-flight and backscattering spectrometers, covering a dynamic range from pico- to nanoseconds. Analysis of the data with localized translational diffusion models shows the existence of a strong confinement effect that depends on geometry. Typical confinement sizes and diffusion coefficients are obtained and compared to Nafion.
[1] S. Lyonnard et al., Eur. Phys. J ST 189, 205-216 (2010).