Homogeneous blend membrane made from poly(ether sulphone) and poly(vinylpyrrolidone) and its application to water electrolysis

A homogeneous blend membrane has been successfully prepared from poly(ether sulphone) (PES) and poly(vinylpyrrolidone) (PVP), which have been usually thought to be immiscible to each other. The PES–PVP membrane possesses combined advantages of the hydrophobic and hydrophilic components; specifically, both good mechanical strength and excellent hydrophilicity have been achieved simultaneously. The success of achieving such special properties can be ascribed to the appropriate choice of solvent for membrane casting, N,N-dimethylformamide (DMF) in this case, and the post-treatment of the membrane in alkaline ethanol solution for obtaining hydrophilicity. Membranes with different blending ratios were characterized with tensile test, scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and electrochemical measurements. The membrane was found to function well as a diaphragm in water electrolysis. In comparison with the traditional asbestos diaphragm, an energy saving of ca. 10% can be reached upon employing PES–PVP membranes in water electrolysis.