QENS investigation of proton confined motions in hydrated perfluorinated sulfonic membranes and self-assembled surfactants
1 Univ. Grenoble Alpes, CNRS/ CEA-INAC-SPrAM, 38000 Grenoble, France
2 Inst Max Von Laue Paul Langevin, 38002 Grenoble, France
3 Univ. Grenoble-Alpes, 38000 Grenoble, France CEA, LITEN, DTNM, 38054 Grenoble, France
a Corresponding author: firstname.lastname@example.org
Published online: 23 January 2015
We report on QuasiElastic Neutron Scattering (QENS) investigations of the dynamics of protons and water molecules confined in nanostructured perfluorinated sulfonic acid (PFSA) materials, namely a commercial Aquivion membrane and the perfluorooctane sulfonic acid (PFOS) surfactant. The former is used as electrolyte in low-temperature fuel cells, while the latter forms mesomorphous self-assembled phases in water. The dynamics was investigated as a function of the hydration level, in a wide time range by combining time-of-flight and backscattering incoherent QENS experiments. Analysis of the quasielastic broadening revealed for both systems the existence of localized translational diffusive motions, fast rotational motions and slow hopping of protons in the vicinity of the sulfonic charges. The characteristic times and diffusion coefficients have been found to exhibit a very similar behaviour in both membrane and surfactant structures. Our study provides a comprehensive picture of the proton motion mechanisms and the dynamics of confined water in model and real PFSA nanostructures.
© Owned by the authors, published by EDP Sciences, 2015
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