Determination of the effect of temperature and humidity on the O2 sorption in sulfonated poly(arylene ether sulfone) membranes

Gas transport properties of O2 in poly(perfluoro sulfonic acid) (Nafion 112) and disulfonated poly(arylene ether sulfone) were compared. While O2 permeabilities were lower in poly(arylene ether sulfone) when compared to poly(perfluoro sulfonic acid), the O2 gas sorption in the former was higher than in Nafion 112. Sorption measurements have been carried out both under non-humidified and humidified conditions. Under non-humidified conditions, the enthalpies of sorption (ΔHs) were calculated as a function of pressure for both Nafion 112 and disulfonated poly(arylene ether sulfone). The |ΔHs| ranged from 6.58 to 7.30 kJ/mol for the disulfonated poly(arylene ether sulfone) and 4.94 to 5.36 kJ/mol for Nafion 112 sample. O2 sorption was also measured as a function of relative humidity and temperature at a normal proton exchange membrane (PEM) fuel cell operating pressure of 1 atm. The disulfonated poly(arylene ether sulfone) was found to have a higher percent O2 mass uptake than Nafion 112. While under dry conditions, O2 sorption followed Henry's law, in the presence of humidity, O2 sorption followed Type IV behavior.