Nafion® is a sulfonated tetrafluorethylene copolymer discovered in the late 1960s by Walther Grot of Du Pont de Nemours. It is the first of a class of synthetic polymers with ionic properties which are called ionomers. Nafion's unique ionic properties are a result of incorporating perfluorovinyl ether groups terminated with sulfonate groups onto a tetrafluoroethylene (Teflon) backbone.