SPEEK-TiO₂ nanocomposite hybrid proton conductive membranes via in situ mixed sol-gel process

Hybrid membranes based on highly sulfonated poly(ether ether ketone) (SPEEK, DS = 0.9) where titania network was dispersed by in situ sol-gel reactions were prepared and characterized. The syntheses were carried out using either a basic catalyst (pyridine) or a chelating agent (2,4-pentandione) to control the features of the inorganic network in the polymeric matrix. Membranes were characterized by thermogravimetric analysis (TG), field emission scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The formation of the inorganic component did not introduce any porosity in the final material and both syntheses led to membranes with enhanced thermal stability, reduced water uptake and good proton conductivity (σ = 5.8 × 10^-2 S cm^-1) up to 120 °C, thus making the samples suitable for application as polymeric electrolytes at intermediate temperature.