Dimensionally Stable Anion Exchange Membranes Based on PPO: Constructing Efficient Ion-Conducting Pathways Combining Rigidity and Flexibility

The trade-off between ionic conductivity and stability remains a major challenge in developing high-performance anion exchange membranes (AEMs). Herein, PPO-based AEMs with an appropriate degree of DABCO-C6 cross-linking and flexible multi-cation DTH side chains, denoted as PPO/DABCO-C6/DTH-y (y = 20–50), were prepared to construct continuous ion-conducting pathways. PPO/DABCO-C6/DTH-40 not only exhibits a high OH– conductivity of 95.75 mS cm–1 at 80 °C and retains 79.79% in 1.0 M NaOH at 80 °C for 600 h but also maintains a low swelling (9.82% at 80 °C) and high tensile strength (37.68 MPa). Raman analysis indicates that OH– transport is primarily governed by the Grotthuss mechanism, enhanced by high alkalinity. In water electrolysis, the PPO/DABCO-C6/DTH-40 achieves 390 mA cm–2 at 1.9 V (50 °C) and remains stable at 420 mA cm–2 (12 h). This study provides a new structural design for PPO-based AEMs, balancing high ionic conductivity with dimensional and chemical stability for practical water electrolysis.