High conductive and dimensional stability proton exchange membranes with an all-carbon main chain and densely sulfonated structure

Sulfonated polyarylene membranes are demonstrated to be efficient as proton exchange membranes (PEMs) for proton exchange membrane fuel cells (PEMFCs) in clean energy conversion systems. In this study, we design and synthesize a series of sulfonated polyarylene with all-carbon backbones and densely sulfonated pendant groups, which can be prepared by copolymerization of 1,3-Disulfonic acid benzaldehyde, 1,1,1-trifluoroacetone and biphenyl under superacid-catalyzed conditions. Rigid, hydrophobic backbone and hydrophilic side chains make the membrane form good microphase separation morphology. The PEMs exhibit high proton conductivity (404 mS cm−1) and excellent dimensional stability (swelling ratio lower than 24% and water uptake lower than 40%) at 80 °C. Moreover, the PEMs show good oxidization stability (the retaining weight rate of membrane up to 99.2% for 1 h oxidative treatment), and the oxidization stability and degradation mechanism of Ar3CH in polymer backbone are also studied. The H2/O2 fuel cell assembled with PEMs exhibited a maximum peak power density of 560 mW cm−2. It indicates that all-carbon main chain and densely sulfonated structure show great potential for improving the performance of PEMs.