Sulfonated Poly(arylene ether sulfone) and Phosphonic Acid-Functionalized Polyhedral Oligomeric Silsesquioxane Composite Membranes for Polymer Electrolyte Membrane Fuel Cells

In this study, an average of 7 phosphoric acid groups capable of transferring hydrogen ions are introduced into polyhedral oligomeric silsesquioxane (POSS) through a substitution reaction, and the prepared POSSs are added to sul-fonated poly(arylene ether sulfone) (SPAES) for a polymer electrolyte membrane for fuel cells with high proton con-ductivity and mechanical properties. As the POSS content in SPAES increases to 5 wt%, the proton conductivity and mechanical properties increase simultaneously. However, when the POSS content exceeds 5 wt%, the two characteristics tend to decrease. This is due to the change in both proton transfer and mechanical load transfer abilities according to the distribution of POSS in SPAES. In conclusion, when 5 wt% of POSS was added to SPAES, it shows a large proton con-ductivity of 3.83x10-1 S cm-1 at 120 degrees C and 100% relative humidity and a high tensile strength of 60 MPa.