Preparation of sulfonated poly(ether ether ketone) (SPEEK) membrane using ethanol/water mixed solvent

Solvent plays an important role in determining the properties of the solution cast membranes. In this work, the sulfonated poly(ether ether ketone) (SPEEK) membranes were prepared via solution casting using the ethanol/water mixed solvent, which exhibited enhanced proton conductivity than those cast from dimethylacetamide (DMAc). With the increase of casting temperature, membrane proton conductivity decreased. The effect of solvent and casting temperature on the membrane properties were further investigated by the scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS) and contact angle measurements. The degree of phase separation was found to be the highest for the SPEEK membranes cast from ethanol/water mixed solvent at the lowest temperature, with the largest amount of sulfonic groups located on the membrane surface. [Display omitted] •Solution casting of SPEEK membranes using environmental friendly solvent.•Enhanced proton conductivity of SPEEK membranes cast from ethanol/water mixed solvent.•Higher degree of phase separation for SPEEK membranes cast at the lower temperatures.