Biomass-Based Composite Anion Exchange Membranes Using Quaternized Chitosan and Quaternized Polydopamine Nanoparticles for Enhanced Performance

Anion exchange membranes (AEMs), which serve as one of the key components in fuel cells, fulfill dual functions: conducting hydroxide ions and blocking the anode and cathode. To balance the relationship between ionic conductivity, mechanical properties, and dimensional stability, quaternized polydopamine (QPDA) nanoparticles were synthesized via a three-step process, including dopamine self-polymerization, grafting with branched polyethylenimine, and quaternization. These QPDA nanoparticles were subsequently used as a novel nanofiller to modify a blend quaternized chitosan (QCS) and polyvinyl alcohol (PVA) polymer, resulting in the QPDA/QCS-PVA composite membranes. The composite samples exhibited improved water uptake, dimensional stability, and ionic conductivity. With the optimal QPDA loading of 6%, the composite membrane achieved a conductivity of 48.4 mS cm −1 at 80°C, which was 2.27 times that of the pure membrane (21.3 mS cm −1 ). The membranes also demonstrated enhanced mechanical properties and alkaline stability, benefiting from the uniform dispersion of QPDA nanoparticles and chemical cross-linking within the composite system. These QPDA/QCS-PVA composite membranes with an optimal balance between performance and stability can be expected to be novel biomass-based AEMs.