Tetrafluoroethylene is copolymerized with a perfluorovinyl ether, containing a functional end group (-SO2F or -CO2CH3) to yield a melt fabricable precursor polymer. After fabrication into the desired shape, the polymer is treated with a solution of potassium hydroxide to convert the functional group to an ion exchange site.
The fundamental incompatibility of the ionic group with the perfluorinated polymer backbone results in a unique morphology, particularly in the presence of water or polar organic solvents. This has been the subject of extensive investigations by various research institutions.
The most important industrial use for these polymers is in the electrolysis of sodium chloride solutions. Initially introduced in order to eliminate the environmental problems of the amalgam process, their performance has now improved to the point where they offer substantial savings, particularly in terms of energy costs, over the two older processes.
An emerging, potentially very important use for perfluorinated ion exchange polymers is as an ionic conductor in fuel cells. Recent advances in this area will be discussed.