Synthesis and testing of a composite membrane based on sulfonated polyphenylene oxide and silica compounds as proton exchange membrane for PEM fuel cells

The present work is an attempt to improve the usseful properties of sulfonated polyphenylene oxide in order to obtain a proton exchange membrane (PEM) for proton exchange membrane fuel cells(PEMFC). Formation of siloxane compounds inside the polymer matrix through an in situ sol-gel process improves properties of the composite membrane: water retention, tensile strength and dimensional stability of the membrane. The presence of the silicone atoms inside the polymer matrix is highlited in the X-ray fluorescence spectra. Parameters related to water absorbtion and proton transport inside the membrane such as: water uptake, hydration number (λ), dimensional expansion by hydration, ion exchange capacity and sulfonation degree show an optimization of the composite membrane compared to the polymeric one. Furthermore, the tensile strength of the composite membranes is better than the polymeric one when both samples are fully hydrated.