Radiation grafting of styrene into crosslinked PTEE films and subsequent sulfonation for fuel cell applications

Proton exchange membranes were prepared by the radiation-induced grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation. The degree of grafting was controlled in the range of 5-75% by the crosslinking density of the PTFE matrix as well as the grafting conditions. The resulting membranes showed a large ion exchange capacity reaching 2.6 meq g-1, which exceeded the performance of commercially available perfluorosulfonic acid films such as Nafion. This will encourage the use of our ion exchange membranes in solid polymer electrolyte fuel cells