Dipole-Cage-Shaped Multication Cross-Linked SEBS-Based Anion Exchange Membrane

Abstract

A series of (dipole-) multicationic cross-linked SEBS-based AEMs were prepared using a multicationic cross-linking strategy with SEBS as the polymer skeleton, which has good alkali stability. By controlling the cross-linking degree, the performance of AEM can be regulated. Introducing a multicationic cross-linking agent DACEE-containing hydrophilic alkoxy chains (dipoles) to improve the performance of the AEMs. The difference in hydrophilicity/hydrophobicity of alkoxy chains in DACEE and the dipole interaction between oxygen atoms and cations contribute to the construction of microphase separation, broadening of ion transport channels, and promoting ion transport efficiency. The steric hindrance of cage-shaped cations in cross-linked structures and the hydrophilicity of alkoxy groups in cross-linking agent DACEE can enhance the alkaline stability of AEMs. The additional intermolecular forces generated after cross-linking enhance the mechanical properties of the cross-linked membrane. Among them, the SEBS-C6TMA-DACEE20% membrane with the best mechanical properties (Ts: 15.37 MPa, Eb: 250.83%) had an OH^– conductivity of 93.61 mS·cm^–1 at 80 °C, and after soaking in 2 M NaOH solution for 1500 h, the OH^– conductivity decreased by 16.3%.