Crosslinked poly (2,6-dimethyl-1,4-phenylene oxide) polyelectrolyte enhanced with poly (styrene-b-(ethylene-co-butylene)-b-styrene) for anion exchange membrane applications

Abstract

Poly (styrene‑b‑(ethylene-co-butylene)‑b‑styrene) (SEBS) shows great potential in anion exchange membranes (AEMs) due to its high chemical stability and flexible mechanical properties, but the trade-off between the ion conductivity and gelation issues greatly impedes further applications. To address this dilemma, we present an effective strategy to enhance comprehensive properties of AEMs by fabricating a crosslinking structure between SEBS and poly (2,6-dimethyl-1,4-phenylene oxide) (PPO). Grafting multiple cations as the side chains ensures the highly efficiently transport of hydroxide. With the addition of SEBS, the crosslinked membranes (T3PPO-c-SEBS) show enhanced physical and chemical properties, such as restrained swelling behavior, firm mechanical properties, great chemical and dimensional stabilities. Obvious hydrophilic/hydrophobic microphase separation morphology is designed to form effective ionic channels for transmitting hydroxide. The T3PPO-c-30%SEBS membrane with 30 wt% content of SEBS exhibits relatively high hydroxide conductivity (24.0 mS/cm at 30 °C) but low swelling ratios (15.6% at 30 °C). Moreover, after the long-time alkaline test (1 M NaOH, 80 °C, 500 h) and antioxidative test (Fenton solution, room temperature, 150 h), the T3PPO-c-30%SEBS membrane shows much better alkaline stability (57.8% retention vs. 24.5%) and oxidative stability (92.0% retention vs. 85.8%) than the pristine T3PPO membrane does. Therefore, T3PPO-c-SEBS can be regarded as promising candidates for AEM applications.