High-Performance and Scalable Anion Exchange Membranes Based on Poly(vinyl alcohol) for Water Electrolysis

High-performance, solution-cast linear anion exchange membranes (AEMs) were fabricated by grafting N¹,N¹,N¹,N⁷,N⁷,N⁷-hexamethyl-4-oxoheptane-1,7-diammonium chloride (HMOHBA) and trifluoromethylbenzaldehyde (TFBA) onto a high-MW poly(vinyl alcohol) (PVA) backbone via acetal/ketal reactions. Optimizing alkyl quaternary ammonium to fluorinated hydrophobic phenyl ratios yielded HMOHBA80-TFBA20-PVA with exceptional properties: 115.9 mS cm^-1 ionic conductivity in water at 80°C; dry-state tensile strength of 58.1 MPa (7.9% elongation); wet-state 29.1 MPa strength with 245.5% elongation. After 1440 h in 1 M KOH at 80°C, the membrane retained 90.4% wet strength, showed 10.5% mass loss, and maintained 90.4% conductivity. In water electrolysis (1 M KOH, 80°C), it achieved 2.05 A cm^-2 at 2.0 V. During 100 hr durability testing at 1 A cm^-2, cell voltage rose minimally from 1.84 to 1.85 V over the final 70 h. This work presents a novel strategy for commercially viable AEMs based on flexible polymer chains.