Crosslinked poly(vinyl alcohol) membranes containing sulfonic acid group: proton and methanol transport through membranes

In the present study, crosslinked poly(vinyl alcohol) (PVA) membranes were prepared using sulfosuccinic acid (SSA) at different crosslinking temperatures. The crosslinked PVA membranes were also synthesized by varying the amount of SSA (5–30 wt.%) in order to achieve desirable proton conductive properties for fuel cell applications. The crosslinked PVA membranes were characterized using an FT-IR spectroscopy, a thermogravimetric analysis (TGA), and a differential scanning calorimetry (DSC). Ion exchange capacities (IECs) of the crosslinked PVA membranes were in the range of 0.5–2.24 mmol/g. The water content was in the range of 10–80%, depending on the amount of SSA containing sulfonic acid group. The proton conductivities and the methanol permeabilities through the membranes were investigated in terms of various crosslinking conditions. Especially, it was found that the SSA used in this study played a decisive role in proton conduction (SO3−H+) and at the same time acted as a barrier for methanol transport. The proton conductivities and the methanol permeabilities of all the membranes were in the range of 10−3 to 10−2 S/cm and 10−7 to 10−6 cm2/s in the temperature range of 25–50 °C, respectively, depending on the crosslinking conditions.