Effect of Dual-Function Crosslinkers on Performance of PECH/PAN Based Anion Exchange Membranes for Reverse Electrodialysis Applications

Abstract

Reverse electrodialysis (RED) is a sustainable technology for salinity gradient energy harvesting, yet its performance is fundamentally constrained by the physicochemical properties of anion exchange membranes (AEMs). The choice of quaternization/crosslinking agent plays a decisive role but remains insufficiently understood in PECH/PAN-based AEMs. In this study, PECH/PAN-based AEMs were synthesized using two dualfunction quaternization and crosslinking agents, 1,4-diazabicyclo[2.2.2]octane (DABCO) and hexamethylenetetramine (HMTA), at different molar ratios, to systematically elucidate both the chemical influence of the crosslinker type on the structure-property-performance relationships. Comprehensive characterization methods, including FTIR, SEM, water uptake (WU), ion exchange capacity (IEC), area resistance, permselectivity, contact angle, gel fraction, tensile strength, and thermogravimetric analysis, were performed. HMTA-based AEMs exhibited low IEC (0.469 meq/g) and WU (12%), resulting in high area resistance (>3000 Omega cm(2)) and low permselectivity (50%). In contrast, DABCO-based AEMs achieved higher IEC (up to 2.27 meq/g), higher WU (35.5%), and significantly lower area resistance (1.58 Omega cm(2)). Among the DABCO based AEMs, D-Q-1 provided nearly ideal permselectivity (99%) through balanced high IEC and low WU, while D-Q-2 delivered the highest IEC and lowest resistance, though at the expense of slightly reduced permselectivity (93%). In RED tests, D-Q-1 yielded the highest open circuit voltage (0.733 V) owing to its highest permselectivity, whereas D-Q-2 produced the highest maximum power density (0.769 W/m2), enabled by reduced area resistance. These results establish clear structure-property-performance correlations and highlight that tailoring quaternization/crosslinking chemistry is a practical route to design next-generation AEMs for efficient RED applications.