By courtesy of:
Bobby R. Ezzell, William P. Carl
US patent 4940525 1987 assigned to The Dow Chemical Company
see also:
Morphology and Chemical Properties of the Dow Perfluorosulfonate Ionomers
Robert B. Moore, III, and Charles R. Martin*
Macromolecules, Vol. 22, No. 9, 3594-9, 1989