Effect of different ion-aggregating structures on the property of proton conducting membrane based on polyvinyl alcohol

Three implementation strategies are designed to investigate the effects of different ion-aggregating structures on the property of proton conducting membrane. Hydrophobic alkyl chains are grafted onto polyvinyl alcohol locating at different places between protons and polymer backbones, which are employed to develop proton conducting membranes with different ion-aggregating structures. The key proton exchange membrane (PEM) parameters, such as ion exchange capacity, proton conductivity, and methanol permeability, are significantly different among these membranes. Notably, the PEM with pendent-type side chain (M2) is in favor of driving the ionic clusters to aggregate and form broad ionic channels, which is confirmed by Anton-paar SAX Sess mc2 system; it displays good proton conductivity (67.8 mS cm−1 at 80 °C). Meanwhile, the PEM with pendulum-type side chain (M3) is beneficial to display excellent tensile strength (22.4 MPa) and alcohol resistance performance (8.98×10−7 cm2 s−1). These findings not only help us to understand the ionic channels in proton exchange membranes, but also provide a strategy for the rational design of polymer membranes.