State of water in nation 117 membranes studied by microwave dielectric relaxation spectroscopy

Zijie Lu, Georgios Polizos, Evangelos Manias, Digby D. Macdonald

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Complex dielectric permittivity spectra, ε*(ω), of hydrated Nafion 117 membranes have been measured using the transmission line method over the frequency range of 0.045-26 GHz and at temperatures ranging from 25 to 45 °C. The spectra were well-fitted by a superposition of one to three Debye relaxation processes, depending on the water content. The first high-frequency dispersion step, with a relaxation time τ≈8 ps at 25 °C, shows the characteristic dynamics of bulk water and is attributed to the cooperative relaxation of hydrogen bonded networks of "free" water in the membrane. The free water is assumed to exist at the center of the ion cluster regions or pores. The second step, having a relaxation time of τ≈30 ps at 25 °C, is attributed to the water molecules in the second hydration shell of the sulfonate ions. The remaining relaxation process occurs at low-frequency, having a relaxation time of τ ≈ 90 ps, and is postulated to result from the motion of the water molecules hydrophobically- associated with the perfluorinated side chains and polymer backbone.

Original languageEnglish (US)
Title of host publicationNanostructured Materials for Energy Storage and Conversion - Proceedings of the International Symposium
Pages211-220
Number of pages10
StatePublished - Dec 1 2008
EventInternational Symposium on Nanostructured Materials for Energy Storage and Conversion - Quebec City, QC, Canada
Duration: May 15 2005May 20 2005

Publication series

NameProceedings - Electrochemical Society
VolumePV 2005-14

Other

OtherInternational Symposium on Nanostructured Materials for Energy Storage and Conversion
CountryCanada
CityQuebec City, QC
Period5/15/055/20/05

All Science Journal Classification (ASJC) codes

  • Electrochemistry

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  • Cite this

    Lu, Z., Polizos, G., Manias, E., & Macdonald, D. D. (2008). State of water in nation 117 membranes studied by microwave dielectric relaxation spectroscopy. In Nanostructured Materials for Energy Storage and Conversion - Proceedings of the International Symposium (pp. 211-220). (Proceedings - Electrochemical Society; Vol. PV 2005-14).