Double-Cation SEBS-Based Anion Exchange Membrane With Ultra-High Ionic Conductivity and Molecular Conformation Simulation Analysis of the Membrane

Using styrene-ethylene-butylene-styrene (SEBS) with a high polystyrene (PS) block ratio as the backbone, a series of highly functionalized side-chain grafted anion exchange membranes (AEMs) were prepared via Blanc chloromethylation and functionalization with a dual-cation group( N , N , N ', N '-tetramethyl-1,2-dimethyl-1,3-propanediamine (DPPA)). Structural simulations of the polymers were conducted using MM2 molecular dynamics. Results demonstrate that the SEBS-DPPA membrane with 100% grafting rate exhibits ultrahigh ionic conductivity, reaching 282.85 mS cm − 1 at 80°C. Molecular simulations reveal continuous high-density ion transport channels formed by quaternized nitrogen atoms within the membrane. The membrane shows ultrahigh ionic conductivity but poor alkali resistance. After immersion in 2 mol L − 1 NaOH solution at 80°C for 1000 h, the ionic conductivity retains only 56.74% of its initial value. Although the ion conductivity decreased by 43.26% after 1000 h of alkali resistance testing, it remained above 150 mS cm − 1 , and the mechanical properties did not show a significant decrease. This indicates that SEBS-DPPA membrane has great potential for application in AEMFCs through further modification. Graphical Grafting double cationic DPPA can form coherent and high-density ion transport channels within SEBS membrane. The ion conductivity of 100% SBES-DPPA membrane can reach 282.85 mS cm −1 at 80°C, which is much higher than the commonly used anion exchange membranes.