Effects of contaminant on thermal properties in perfluorinated sulfonic acid membranes

The influence of controlled cationic contaminant on the thermal behaviour of proton conducting perfluorosulfonic acid membrane (PFSA) was studied. A series of Ni2+-exchanged membrane was prepared by varying the ratio between positive charges resulting from the contaminant to the negative charges originating from the sulfonate groups. A large change in properties was evidenced at a ratio close to 0.2. Above this threshold, the PFSA exhibited significantly higher main relaxation and degradation temperatures. The set of experimental data could be described with the help of a phenomenological microstructural model essentially based on ionic interactions. The impurity model could then be employed to understand changes in protonic conductivity from the literature.