Proton Conducting Organic/Inorganic Sol–Gel Membranes Produced from Phenyltriethoxysilane and 3-Methacryloxypropyl Trimethoxysilane

The increase of the operation temperature in Proton Exchange Membrane Fuel Cells (PEMFC) above 100∘C would be an important breakthrough for the application of this type of fuel cell in electric vehicles. Hybrid organic-inorganic membranes with nano-sized interfaces can combine all the properties to meet this objective. Membranes using phenyltriethoxysilane and 3-methacryloxypropyl trimethoxysilane have been synthesised by polymerisation of methacrylate groups and inorganic condensation of silanol groups. Sulfonation process to provide proton conductivity affects both proton conductivity and chemical stability of hybrid membranes. Liquid sulfonation during the sol preparation and chlorosulfonic acid as sulfonating agent leads to chain cleavage while trimethylsilyl chlorosulfonate does not affect the polymer backbone. The increase of temperature (up to 120–130∘C) and relative humidity leads to an increase of proton conductivity close to 10− 3 S/cm.