Measurement and controlling the residual solvent of sulfonated poly ether ether ketone proton exchange membrane

Nowadays using renewable and clean energy is one of the targets of researchers. One of these modern energy convertor is proton exchange membrane fuel cell (PEMFC) with minimum harm to the environment. Proton exchange membranes (PEM) could be categorized into perfluorinated and nonfluorinated hydrocarbon based on the material. Sulfonated Poly-Ether-Ether-Ketone (SPEEK) which is a hydrocarbon PEM was used in this research because of its low cost , good accessibility and high thermal stability (1). SPEEK membrane usually prepared by the solution casting method. In this method the polymer is dissolved in a solvent and casted. The solvent is supposed to evaporate through the casting process. However, an amount of solvent would remain in the casted membrane after drying that is called residual solvent (RS). It is noteworthy that RS content affects many of membrane electrochemical and structural properties and are the main focus of the recent studies in this field (2). Dimethylformamide (DMF), dimethylsulfoxide (DMSO), Dimethylacetamide (DMAc) and Nmethyl-2-pyrrolidone (NMP), are the most commonly used solvents for casting membranes. These solvents interact differently with the membrane. Hence the amount of RS content in the membrane casted with each of them would differ. In this research the amount of RS in the membrane casted with various solvent is measured. Additionally, acidic and thermal treatment were used to reduce the RS.