Nafion

Nafion
Chemical Structure of Nafion
Identifiers
ChemSpider
  • none
Properties
C7HF13O5S . C2F4
Molar mass See Article
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H319, H335
P261, P264, P271, P280, P304+P340, P305+P351+P338, P312, P337+P313, P403+P233, P405, P501
Related compounds
Related compounds
 Aciplex
Flemion
Dowex
fumapem F
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Nafion is a brand name for a sulfonated tetrafluoroethylene based fluoropolymer-copolymer synthesized in 1962 by Dr. Donald J. Connolly at the DuPont Experimental Station in Wilmington Delaware (U.S. Patent 3,282,875). Additional work on the polymer family was performed in the late 1960s by Dr. Walther Grot of DuPont.[1] Nafion is a brand of the Chemours company. It is the first of a class of synthetic polymers with ionic properties that are called ionomers. Nafion's unique ionic properties are a result of incorporating perfluorovinyl ether groups terminated with sulfonate groups onto a tetrafluoroethylene (PTFE) backbone.[2][3][4] Nafion has received a considerable amount of attention as a proton conductor for proton exchange membrane (PEM) fuel cells because of its excellent chemical and mechanical stability in the harsh conditions of this application.

The chemical basis of Nafion's ion-conductive properties remain a focus of extensive research.[2] Ion conductivity of Nafion increases with the level of hydration. Exposure of Nafion to a humidified environment or liquid water increases the amount of water molecules associated with each sulfonic acid group. The hydrophilic nature of the ionic groups attract water molecules, which begin to solvate the ionic groups and dissociate the protons from the -SO3H (sulfonic acid) group. The dissociated protons "hop" from one acid site to another through mechanisms facilitated by the water molecules and hydrogen bonding.[2] Upon hydration, Nafion phase-separates at nanometer length scales resulting in formation of an interconnected network of hydrophilic domains which allow movement of water and cations, but the membranes do not conduct electrons and minimally conduct anions due to permselectivity (charge-based exclusion). Nafion can be manufactured with or exchanged to alternate cation forms for different applications (e.g. lithiated for Li-ion batteries) and at different equivalent weights (EWs), alternatively considered as ion-exchange capacities (IECs), to achieve a range of cationic conductivities with trade-offs to other physicochemical properties such as water uptake and swelling.

  1. ^ Church, Steven (January 6, 2006). "Del. firm installs fuel cell". The News Journal. p. B7.
  2. ^ a b c Kusoglu, Ahmet; Weber, Adam Z. (2017-02-08). "New Insights into Perfluorinated Sulfonic-Acid Ionomers". Chemical Reviews. 117 (3): 987–1104. doi:10.1021/acs.chemrev.6b00159. ISSN 0009-2665. PMID 28112903.
  3. ^ Heitner-Wirguin, C. (1996). "Recent advances in perfluorinated ionomer membranes: structure, properties and applications". Journal of Membrane Science. 120 (1): 1–33. doi:10.1016/0376-7388(96)00155-X.
  4. ^ Cite error: The named reference Mauritz2004 was invoked but never defined (see the help page).