Local hydration in ionomer composite membranes determined with confocal Raman microscopy

Abstract: Water management in electrochemical energy applications like fuel cells has a crucial impact on performance, in particular on the ionic conduction of ionomer membranes. To strengthen the understanding of water management in such devices, we report a novel method for non-destructive measurements of the hydration of composite membranes based on confocal Raman microscopy. Composite membranes were produced by spray-coating of Nafion into a mesh of electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/polyvinylpyrrolidone (PVDF-HFP/PVP) blend nanofibers. Hydration levels of several pure nanofiber meshes and nanofiber/Nafion composites were evaluated by linear least squares fitting of reference Raman spectra to hyperspectral images. We found that spectral contribution of water to nanofiber spectra depends on the PVDF-HFP/PVP ratio and is independent from fiber diameter. Further, we were able to reliably determine nanofiber polymer composition of single fibers based on Raman spectroscopy. Raman imaging of composite membranes was performed at ambient air and fully hydrated conditions to study the local hydration in PVDF-HFP/PVP/Nafion composites as well as in a Nafion XL membrane. 2D through-plane mappings revealed that the nanofiber hydration positively correlated with PVP content. In the Nafion XL membrane, the polytetrafluoroethylene-based reinforcement was verified as a hydrophobic layer sandwiched between Nafion ionomer, which showed a more than 10% reduced hydration compared to the outer Nafion layers. These results motivate the use of confocal Raman microscopy as a novel method to investigate the local water distribution in ionomer composite membranes that are widely used in electrochemical energy conversion

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Journal of membrane science. - 585 (2019) , 126-135, ISSN: 0376-7388

Classification and Topics

• Keyword: Konfokale Mikroskopie ; Membran ; Hydratation ; Hydratisierung

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2020
• Creator: Solihul Mumin, Muhammad ; Böhm, Thomas ; Moroni, Riko ; Zengerle, Roland ; Thiele, Simon ; Vierrath, Severin ; Breitwieser, Matthias
• Contributor: Albert-Ludwigs-Universität Freiburg. Professur für Anwendungsentwicklung

Further information

• DOI: 10.1016/j.memsci.2019.05.032
• URN: urn:nbn:de:bsz:25-freidok-1528306
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 15.08.2025, 7:26 AM CEST