Anomalous behavior of proton transport and dimensional stability of sulfonated poly(arylene ether sulfone) nonwoven/silicate composite proton exchange membrane with dual phase co-continuous morphology

Herein, anomalous behavior of proton conductivity and dimensional stability of sulfonated poly(arylene ether sulfone) (SPAES) nanofiber nonwoven fabric/silicate composite membrane (denoted as ‘SN/S membrane’) featuring dual phase co-continuous morphology, which could be potentially applied to proton exchange membrane fuel cells (PEMFCs), is systematically investigated. The SN/S membrane is fabricated via in situ sol–gel synthesis of tetraethoxysilane (TEOS)/3-glycidyloxypropyltrimethoxysilane (GPTMS) mixture directly inside the electrospun SPAES nonwoven. In comparison to a typical SPAES (matrix)/silicate (domain) composite membrane, the SN/S membrane having structural uniqueness provides significant improvement in relative humidity (RH) variation-driven dimensional change, although its proton conductivity is decreased due to the presence of ionically inert continuous silicate phase. A noteworthy finding of this study is that the phase morphology of composite proton exchange membranes plays a crucial role in determining the membrane properties such as proton conductivity and dimensional stability. [Display omitted] •SPAES/silicate composite membranes with dual phase co-continuous morphology.•In situ sol–gel synthesis of TEOS/GPTMS mixture inside electrospun SPAES nonwovens.•The unique phase structure brings anomalous behavior of membrane properties.•The composite membranes show noticeable improvement in dimensional change.•Proton conductivity of the membranes is slightly impaired due to the silicate phase.