Perfluorosulfonic acid ionomer transport properties

Kreuer et al. [25] investigated the membrane properties, including water sorption, transport (proton conductivity, electro-osmotic water drag and water diffusion), microstructure and viscoelasticity of the short-side-chain (SSC) perfluorosulfonic acid ionomers (PFSA, Dow 840 and Dow 1150) with different lEC-values. The data were compared to those for Nafion 117, and the implications for using such ionomers as separator materials in direct methanol and hydrogen fuel cells discussed. Tire major advantages of PFSA membranes were seen to be (i) a high proton conductivity. 

Pellegrino J, Wang D, Rabago R, Noble RD, Koval CA. Gas transport properties of solution-cast perfluorosulfonic acid ionomer films containing ionic surfactants. J Membr Sci 1993 84 161-169. 

Polymer electrolyte fuel cells (PEFCs) are unique in that they are the only variety of low-temperature fuel cell to utilize a solid electrolyte. The most common polymer electrolyte used in PEFCs is Nafion , produced by DuPont, a perfluorosulfonic ionomer that is commercially available in films of thicknesses varying from 25 to 175 pm. This material has a fluorocarbon polytetrafluoroethylene (PTFE)-kbone with side chains ending in pendant sulfonic acid moieties. The presence of sulfonic acid promotes water uptake, enabling the membrane to be a good protonic conductor, and thereby facilitating proton transport through the cell. This chapter reviews PEFC development, structure, and properties and presents an overview of PEM technology to date. 

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