Impact of Double Crosslinking and Alkaline Activation Strategies towards the Multifaceted Characteristics of Quaternized Poly(vinyl alcohol) Anion Exchange Membrane

Abstract

This study investigates the effects of crosslinking strategies and KOH activation on the multifaceted characteristics of quaternized poly(vinyl alcohol) (QPVA) membranes for anion exchange membrane (AEM) applications. In-situ and combined in-situ/ex-situ crosslinking with glutaraldehyde were evaluated at 5M, 6M, and 8M KOH concentrations. Multifaceted characteristics on the membranes including ionic conductivity, swelling degree, thermal and oxidative stability are studied. The M1 5M KOH membrane (in-situ crosslinked, heated activation) demonstrated the highest ionic conductivity (40.93 mS/cm before equilibrium, 33.41 mS/cm after equilibrium) and moderate oxidative stability (81.10%). Combined crosslinking and higher activation temperatures improved membrane stability and mechanical properties but reduced oxidative stability owing to potential alkaline attack on glutaraldehyde crosslinked groups. The novelty of this work lies in the dual crosslinking strategy, which significantly enhances the mechanical and thermal properties of QPVA membranes, while also highlighting the impact of KOH activation on crystallinity and ion transport. This study highlights the importance of optimizing crosslinking and activation conditions to develop high-performance QPVA membranes for AEM applications.