Natural Comb‐Shaped Polyvinyl Butyral Anion Exchange Membranes With Bulky Cations for Enhanced Performance

ABSTRACT In this study, a novel ether‐free natural comb‐like polyvinyl butyral‐based anion exchange membrane (AEM) was synthesized via the Mitsunobu reaction, aiming to achieve a balanced combination of alkaline stability, ionic conductivity, and mechanical strength. To improve the structural integrity of the material and promote microphase separation, benzimidazole (BIM) and benzotriazole (BTA), both featuring rigid conjugated frameworks, were incorporated into the polymer matrix. Experimental results demonstrated that the Q‐PVB‐BIM 0.6 membrane achieved a hydroxide ion conductivity of 71.28 mS cm −1 at 80°C. Furthermore, after immersion in 2 M NaOH solution for 1200 h, the membrane retained 78.8% of its initial conductivity, confirming its excellent alkaline stability. This remarkable performance can be attributed to the synergistic effects of charge delocalization and steric hindrance provided by the BIM cation. In contrast, the Q‐PVB‐BTA 0.6 membrane retained 70.6% of its original ionic conductivity under the same conditions, which may result from the higher electron density of the triazole ring, rendering it more susceptible to nucleophilic attack by hydroxide ions. However, the Q‐PVB‐BTA 0.6 membrane exhibited superior mechanical strength (21.75 MPa), likely due to the presence of π–π stacking interactions. Through a systematic comparative analysis, this study offers a comprehensive understanding of how different heterocyclic structures influence the electrochemical and mechanical properties of AEMs.