Nafion

Structural formula
General
Surname	Nafion
other names	2- [1- [Difluoro [(trifluoroethenyl) oxy] methyl] -1,2,2,2-tetrafluoroethoxy] -1,1,2,2-tetrafluoroethanesulfonic acid
CAS number	31175-20-9
Monomers / partial structures	Perfluoro-3,6-dioxa-4-methyl-7-octene-1-sulfonic acid; Tetrafluoroethylene;
Type of polymer	Ionomer
Brief description	colorless to pale brown solid
properties
Physical state	firmly
density	1.98 g cm −3
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 319-335
	P: 261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Nafion is a perfluorinated copolymer that contains a sulfo group as an ionic group . It was developed in the late 1960s by Walther Grot as a modification of Teflon . Nafion is one of the ionomers and is a registered trademark of DuPont .

properties

The strongly acidic sulfonic acid groups in the Nafion enabled a perfluorinated polymer with ionic properties for the first time. It shows some characteristics that differ fundamentally from those of Teflon while maintaining the high chemical resistance:

rapid diffusion of water and alcohols, but hydraulically tight
selectively conductive for protons and other cations ( blocking effect for anions)
high operating temperatures compared to other polymers (up to 190 ° C)

Technical applications for Nafion membranes

Ion exchangers - membranes in chlor-alkali electrolysis
Drying or humidification of gases due to its high selectivity and permeability for water (vapor)
Proton exchange membrane in polymer electrolyte and direct methanol fuel cells
Production of chromic acid and regeneration of contaminated chromium baths
Production of potassium dicyanido aurate (I) by dissolving a gold anode in potassium cyanide (KCN)
As a strongly acidic, solid catalyst

Like other perfluorinated exchange materials, Nafion largely loses its proton conductivity from a temperature of 100 ° C and in direct methanol fuel cells shows too high a permeability for water and methanol.

Web links

Nafion properties ( Memento from August 1, 2013 in the Internet Archive )
What is Nafion? ( Memento from September 27, 2011 in the Internet Archive )

Trade names

Nafion (DuPont)
Flemion (Asahi)

Individual evidence

↑ ^a ^b ^c Data sheet Nafion ^® NR50 from Sigma-Aldrich , accessed on April 12, 2011 ( PDF ).
↑ DuPont Fuel Cells: DuPont Nafion PFSA Membranes , accessed September 22, 2019.
↑ Flemion (Fluoropolymer Ion-Exchange Membrane) ( Memento from December 1, 2016 in the Internet Archive )

[Sigma-1] Data sheet Nafion ^® NR50 from Sigma-Aldrich , accessed on April 12, 2011 ( PDF ).

[2] DuPont Fuel Cells: DuPont Nafion PFSA Membranes , accessed September 22, 2019.

[3] Flemion (Fluoropolymer Ion-Exchange Membrane) ( Memento from December 1, 2016 in the Internet Archive )