Sulfonated poly(ether ether ketone)/ethylene glycol/polyhedral oligosilsesquioxane hybrid membranes for fuel cell applications

The paper describes the preparation of hybrid membranes using a trisilanol phenyl polyhedral oligosilsesquioxane (TSP POSS) as filler, ethylene glycol (EG) as cross-linker and sulfonated poly(ether ether ketone) [SPEEK] (DS ∼65%) as polymer matrix. The performance of membranes has been evaluated in terms of thermal stability [by thermogravimetric analysis (TGA), differential scanning calorimetery (DSC)], water uptake, proton conductivity and X-ray diffraction (XRD) analysis. Morphology of the membranes has been investigated using scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and atomic force microscopy (AFM). The addition of EG has increased the proton conductivity and dimensional stability of SPEEK matrix whereas incorporation of a small amount of TSP POSS to SPEEK/EG membranes has resulted in the decrease in water uptake and proton conductivity of the hybrid membranes. ► SPEEK (DS ∼65%) based cross-linked composite membranes are prepared. ► Ethylene glycol is used as cross-linker and TSP POSS as filler to prepare membranes. ► XSP/EG/TSP POSS-2.0 is the best performing membrane in this work.