The effect of ionic bond on anion exchange membrane: Enhanced hydrophilicity and structural rearrangement of blending membrane

Abstract

For the commercialization of anion exchange membrane fuel cells (AEMFCs), the anion exchange membrane (AEM), which is a key component of AEMFCs, requires not only excellent ion conductivity but also high alkaline stability. Therefore, in this study, a hybrid membrane composed of quaternized poly(phenylene oxide) (QPPO) with a dense ion sites and polyvinyl alcohol (PVA), known for its superior chemical and mechanical properties, is prepared. The QPPO_x-PVA_y AEMs (where x and y represent the weight ratio of QPPO and PVA) forms hydrogen bonds or electrostatic interactions through a dehydration reaction between the quaternary ammonium group of QPPO and the hydroxyl group of PVA. This network bonding, resulting in enhanced hydrophilicity and structural rearrangement, improves the dimensional and chemical stability of the membrane. Among the prepared AEMs, QPPO₈₅-PVA₁₅ AEM exhibits high ionic conductivity of 79.8 mS cm⁻¹ at 80 °C under 100 % RH, a low dimensional change, and appropriate mechanical strength. In addition, ion conductivity of QPPO₈₅-PVA₁₅ AEM retains 86.3 % of its initial ion conductivity after 1000 h in 2 M NaOH conditions. Thus, overall results demonstrate that the appropriate incorporation of PVA is effective in producing AEMs with excellent dimensional stability and high performance.