Stabilization of sulfonated aromatic polymer (SAP) membranes based on SPEEK-WC for PEMFCs

In this work dense polymer electrolyte membranes (PEM) were prepared by casting and solvent evaporation from homogeneous solutions of the sulfonated derivative of an amorphous polyetheretherketone, known as SPEEK-WC. In order to obtain stabilized PEMs, the SPEEK-WC membranes were modified by following three different strategies: thermal annealing, chemical cross-linking with a diamine and blending with Nafion ionomer. Various ex situ characterizations were carried out on the modified and reference SPEEK-WC membranes, including: ion exchange capacity, proton conductivity, liquid water uptake, counter elastic index, chemical resistance in oxidative conditions, and gas permeability. The results indicated that the first two methodologies are able to increase hydrolytic and oxidative stability of the SPEEK-WC membranes at a temperature higher than 100 °C.