Flexible Sulfonic Acid-Functionalized Polybenzimidazole Membranes with Enhanced High-Temperature and Dimensional Stability for Electrodialysis Desalination

Given the pressing need for enhancing industrial energy efficiency and process intensification, membrane separation technology possesses significant application potential in industrial waste heat recovery and resource utilization. A thermally stable polybenzimidazole (PBI) with a tribranched topology was functionalized via two strategies: direct sulfonation (ds-tzPBI) and flexible side-chain sulfonation (ls-tzPBI). The effects of sulfonation were systematically investigated, revealing that the resulting ls-tzPBI-1.0 membrane maintained an excellent structural integrity and ion transportability under elevated temperatures (80 °C). This design effectively balances stability and separation efficiency at high temperatures, offering a promising solution for industrial heat recovery.