Improved performance of acid-base composite of phosphonic acid functionalized polysulfone and triazolyl functionalized polysulfone for PEM fuel cells

The synergetic proton conducting effect was observed in an acid-base composite composed of phosphonic acid functionalized polysulfone (PSF-PA) and triazolyl functionalized polysulfone (PSF-CH 2 -iPrOHTri), with three orders of magnitude improvement compared to that of the acidic or basic component. The maximum proton conductivity of 42.71   mS   cm −   1 at 100   °C and 90% RH was observed in PSF-PA/PSF-CH 2 -iPrOHTri composite membrane composed of 75.0% PSF-CH 2 -iPrOHTri. In addition, the acid-base composite membrane showed higher thermal and oxidative stability , reduced hydrophilicity and methanol permeability , significantly improved mechanical strength . For the hydrated membranes of PSF-PA or PSF-CH 2 -iPrOHTri, the tensile strengths showed significant degradation with values only about halves of the dry membranes. On the other side, the tensile strength of the acid-base composite composed of 75.0% PSF-CH 2 -iPrOHTri showed only slight drop from 35.52   MPa to 30.59   MPa.