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.