Effect of Sulfonation Conditions on Properties of Ion-Conducting Membranes Based on Polystyrene Grafted on Gamma-Irradiated Polyvinylidene Fluoride Films

The process of heterogeneous sulfonation of a radiation-grafted copolymer of polystyrene and polyvinylidene fluoride depending on the reaction time and the type of sulfonating agent (chlorosulfonic acid or its equimolar mixture with acetic acid) has been studied. The water uptake, ion-exchange capacity, and ionic conductivity of the prepared membranes have been characterized. In addition, composition and morphology of materials at different synthesis stages have been analyzed by FTIR, 1Н NMR, and EPR spectroscopies, elemental analysis, and scanning electron microscopy combined with energy dispersive X-ray microanalysis. The ionic conductivity of the prepared materials exceeds that of Nafion®212 membranes. In addition, the mechanical properties and hydrogen gas permeability of the membrane with the highest ionic conductivity (52 mS/cm at 80°C in contact with water) are better than those of the Nafion®212 membrane.