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. (C) 2010 Elsevier B.V. All rights reserved.