New Nanocomposite Hybrid Inorganic–Organic Proton‐Conducting Membranes Based on Functionalized Silica and PTFE

Two types of new nanocomposite proton‐exchange membranes, consisting of functionalized and pristine nanoparticles of silica and silicone rubber (SR) embedded in a polytetrafluoroethylene (PTFE) matrix, were prepared. The membrane precursor was obtained from a mechanical rolling process, and the SiO 2 nanoparticles were functionalized by soaking the membranes in a solution of 2‐(4‐chlorosulfonylphenyl)ethyl trichlorosilane (CSPhEtCS). The membranes exhibit a highly compact morphology and a lack of fibrous PTFE. At 125 °C, the membrane containing the functionalized nanoparticles has an elastic modulus (2.2 MPa) that is higher than that of pristine Nafion (1.28 MPa) and a conductivity of 3.6×10 −3  S cm −1 despite a low proton‐exchange capacity (0.11 meq g −1 ). The good thermal and mechanical stability and conductivity at T >100 °C make these membranes a promising low‐cost material for application in proton‐exchange membrane fuel cells operating at temperatures higher than 100 °C.