Pyrrolidinium‐Based Hyperbranched Anion Exchange Membranes with Controllable Microphase Separated Morphology for Alkaline Fuel Cells.

It is well acknowledged that the microphase‐separated morphology of anion exchange membranes (AEMs) is of vital importance for membrane properties utilized in alkaline fuel cells. Herein, a rigid macromolecule poly(methyldiallylamine) (PMDA) is incorporated to regulate the microphase morphology of hyperbranched AEMs. As expected, the hyperbranched poly(vinylbenzyl chloride) (HB‐PVBC) is guided to distribute along PMDA chains, and longer PMDA cha leads to a more distinct microphase morphology with interconnected ionic channels. Consequently, high chloride conductivity of 10.49 mS cm−1 at 30 °C and suppressed water swelling ratio lower than 30% at 80 °C are obtained. Furthermore, the β‐H of pyrrolidinium cations in the non‐antiperiplanar position increases the energy barrier of β‐H elimination, leading to conformationally disfavored Hofmann elimination and increased alkaline stability. This strategy is anticipated to provide a feasible way for preparing hyperbranched AEMs with clear microphase morphology and good overall properties for alkaline fuel cells. [ABSTRACT FROM AUTHOR]