Hybrid Organic/Inorganic Sol-Gel Materials for Proton Conducting Membranes

One important application of hybrid organic-inorganic materials with nano-sized interfaces is the preparation of membranes for Proton Exchange Membrane Fuel Cells (PEMFC) operating at high temperature. Poly (styrene-co-methacrylate)--silica covalent hybrid membranes have been synthesised by copolymerization of monomers (styrene and 2-hydroxyethyl methacrylate), with formation of covalent bonds between hydroxyl group of HEMA and pre-hydrolysed tetraethoxysilane (TEOS). Sulfonation of benzyl groups was applied to endow the membranes of proton conductivity. The incorporation of an inorganic component to a polymeric one modifies properties like thermal, chemical and mechanical stability, and proton conductivity. A compromise between these properties has to be achieved to produce adequate proton conducting membranes with application in PEMFC. The hybrid membrane with 25% SiO2 combines these properties being a promising candidate for application in PEMFC.