Perfluorosulfonic acid ionomer

So, the particles have at least one dimension that is less than 200 nm. The use of nanoparticles was found to improve the performance of the membrane assemblies compared to assemblies using macroparticles. As ionomers, perfluorosulfonic acid polymers, e.g., poly-(tetrafluoroethylene-perfluorosulfonyl fluoride), can be used (153). 

The electrolyte is a perfluorosulfonic acid ionomer, commercially available under the trade name of Nafion . It is in the form of a membrane about 0.17 mm (0.007 in) thick, and the electrodes are bonded directly onto the surface. The elec trodes contain veiy finely divided platinum or platinum alloys supported on carbon powder or fibers. The bipolar plates are made of graphite or metal. 

The evaluation of catalysts typically uses two techniques. The first is evaluation as a thin layer on a bulk electrode (e.g., glassy carbon) in dilute liquid electrolyte (e.g., H2 4) either as a static electrode or an RDE. In the study of oxygen reduction, there has been much discussion as to the most appropriate electrolyte to use. In general, dilute perchloric acid (HCIOJ is preferred because of its noncoordinating nature, it is thus closest to the environment foxmd within a FEM catalyst layer with perfluorosulfonic acid ionomer. A possible alternative is trifluoromethylsulfonic acid (CF3SO3H), which mimics perfluorosulfonic acids closely, but there are relatively few studies with this acid. Rotating... 

Savett, S. C., Atkins, J. R., Sides, G. R., Harris, J. L., Thomas, B. H., Greager, S. E., Pennington, W. T. and DesMarteau, D. D. 2002. A comparison of [(perfluoroalkyl) sulfonyl] imide ionomers and perfluorosulfonic acid ionics for applications in PEM fuel-cell technology. Journal of the Electrochemical Society 149 A1527-A1532. 

Mauritz, K. A., Stefanithis, I. D., Davis, S. V., Scheetz, R. W, Pope, R. K., Wilkes, G. L. and Huang, H. H. 1995. Microstructural evolution of a silicon-oxide phase in a perfluorosulfonic acid ionomer by an in situ sol-gel reaction. Journal of Applied Polymer Science 55 181-190. 

An adequate structure of polymer molecules promotes the advantageous phase separation into hydrophobic and hydrophilic domains upon water uptake. The most notable class of membranes based on this principle are the perfluorosulfonic acid ionomers (PFSI), Nafion [26] and similar membranes [27]. In these membranes, perfluorosulfonate side chains, terminated with hydrophilic —SO3H groups, are attached to a hydrophobic fluorocarbon backbone. The tendency of ionic groups to aggregate into ion clusters due to the amphiphilic nature of the ionomer leads to the formation of basic aqueous units. At sufficient humidity these units first get connected by narrow channels and then may even fuse to provide continuous aqueous pathways [28]. 

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. 

The advent of Du Pont s inert perfluorosulfonic acid membranes, Nafion, in the late 1960,s made chlor-alkali production in a membrane cell a realistic possibility. The basic structure of Du Pont s fluoro ionomer is shown... 

S.C. Savett, J.R. Atkins, C.R. Sides, J.L. Harris, B.H. Thomas, S.E. Creager, W.T. Pennunington and D.D. DesMarteau, A comparison of bis[(perfluoroalkyl)-sulfonyl]-imide ionomers and perfluorosulfonic acid ionomers for applications in PEM fuel-technology, J. Electrochem. Soc., 2002, 149, A1527-A1532. 

Nafion -type ionomer materials, we evaluated the use of perfluorosulfonic acid... 

Cation-exchange membranes, perfluorosulfonic acid ionomer, 125... 

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 membrane Polymer electrolyte membrane fuel cell Pulse field gradient NMR spectroscopy Perfluorosulfonic acid ionomer... 

Numerous polymers have been studied for their potential apphcation in PEMFCs. Based on their chemical structure, these polymers can be categorized into (a) vinylic polymers, (b) aromatic polymers, and (c) polymer blends and composite/hybrid polymers. Generally, vinylic polymers are synthesized by addition polymerization, while aromatic polymers are synthesized by step-growth polymerization. The most studied vinylic polymers for PEMFC applications are perfluorosulfonic acid ionomers (PFSls), in particular Nation , and styrene sulfonic acid-based polymers. Chemical structures of representative vinyhc PEMs are shown in Scheme 2. 

R.A. Zoppi, I.V. P. Yoshida, S. P. Nunes, Hybrids of perfluorosulfonic acid ionomer and silicon oxide by sol-gel reaction from solution Morphology... 

Subianto S, Cavaliere S, Jones D J and Rozidre J (2013), Effect of side chain length on the electrospinning of perfluorosulfonic acid ionomers . Polymer, 51,118-128. 

J.H. Han, K.W. Lee, G.W. Jeon, C.E. Lee, W.K. Park, E.H. Choi, H nuclear magnetic resonance study of hydrated water dynamics in perfluorosulfonic acid ionomer NAFION, Appl. Phys. Lett. 106 (2015) 023104. 

K.D. Kreuer, M. Schuster, B. Obliers, O. Diat, U. Traub, A. Fuchs, U. Klock, S.J. Paddison, J. Maier, Short-side-chain proton conducting perfluorosulfonic acid ionomers why they perform better in PEM fuel cells, J. Power Sources 178 (2008) 499-509. 

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