Plasma-treated phosphonic acid-based membranes for fuel cell

• New polymer blend membranes containing phosphonic acid groups have been prepared.
• High proton conductivity and good thermal stability have been demonstrated.
• Argon plasma treatment has enabled to improve blend membrane properties.
• Plasma-treated blend membranes appear as good candidates for PEMFC.

In the highly competitive market of fuel cells, proton exchange membrane fuel cells operating in the range 80–150 °C seem quite promising. One of the main hurdles for emergence of such a technology is the development of phosphonic acid-based membranes characterized by high conductivity and stability beyond 80 °C. In this work, new polymer blend membranes mixing a fluorinated polymer (poly(VDF-co-CTFE)) and a phosphonated polymer (poly(CTFE-alt-DEVEP)) have been prepared at low cost. High proton conductivity (40 mS m−1 at 80 °C, 100% HR) and good thermal stability, directly related to the specific structuration of membranes, have been demonstrated. Due to cross-linking effect, argon plasma treatment of blend membranes has enabled to improve their thermal stability and fuel retention without altering their morphology, chemical composition and proton conductivity. Plasma-treated blend membranes appear as good candidates for PEMFC, as shown by preliminary fuel cell tests.