Construction of Cross-Linked Poly(aryl Ether Nitrile) Anion Exchange Membranes Containing Bilateral Linked Branches for Water Electrolyzer

The anion exchange membranes (AEMs) serving as the core component play critical roles in the water electrolyzer, but the trade-off between ion conductivity and dimensional stability of AEMs remains a huge obstacle. Herein, a series of double-chain dendritic cross-linked poly(aryl ether nitrile) AEMs were prepared through the introduction of 1-allyl-3-methylimidazole chloride salt and 1-vinylimidazole. The rational molecular structure design, unique nitrile groups on the backbone, and direct grafting of hydrophobic side chains contributed to the dimensional stability, regulation of the functional cation content, and ion transport channels of the membranes. It was found that the CS-G-PAENA-X AEMs exhibited the anticipated characteristics of a high ion exchange capacity (2.46–3.01 mmol/g) and superior hydroxide conductivity (61.51–129.87 mS/cm at 80 °C). The water uptake and swelling ratio of the CS-G-PAENA-X AEMs were in the ranges 16.67–37.22 and 1.95–4.59%, respectively. In water electrolysis test, the AEM achieved a peak current density of 492.63 mA/cm2 in 1 M KOH solution. This work provides an alternative approach to prepare high performance AEMs and shows potential application in a water electrolyzer.