Highly conductive and stable anion-exchange membranes based on crosslinked poly(arylene ether sulfone)-block-poly(phenylene oxide) Networks

In the field of the developments of next-generation polymer electrolyte membranes, high conductivity is often regarded as the first important performance requirement. There is still a huge challenge to face, which is hard to achieve the balance between high ion conductivity (mainly related to ion-exchange capacity [IEC]) and good mechanical-dimensional stability (represented by swelling ratio [SR]). Here, a family of crosslinked block polyelectrolytes consisting of hydrophobic rigid poly(arylene ether sulfone) segments to ensure enough dimensional stability and hydrophilic poly(phenylene oxide) segments bearing long-flexible chains with high-density multications to serve as crosslinker and carrier for ion transport are prepared. The polyelectrolyte with an IEC of  3.04 mmol g −1 exhibits a high hydroxide conductivity of 126 mS cm −1 and a low SR of 8.6% at 80 °C. No obvious degradation below 200 °C is observed, and maximum tensile strength reaches 28.4 MPa. As a conclusion, these crosslinked membranes based on well-designed block polyelectrolytes exhibit an excellent combination of high ion conductivity and good mechanical-dimensional stability to meet the performance requirements for the application of anion-exchange membranes. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58 , 391–401 Graphical The novel anion-exchange membranes (AEMs) having a unique crosslinked “ladder-like” chemical structure are prepared after a series of chemical reactions. Continuous conductive domains from hydrophilic areas are beneficial to OH − transport owing to locally high concentration of cations gathering. The medium-length densely crosslinked chains not only ensure the flexibility of AEMs, but also limit the excessive swelling ratio at high temperature. Meanwhile, the crosslinked AEMs exhibit improved alkaline stability due to the hindrance to OH − attack. In a word, the block polyelectrolytes with crosslinked hydrophilic segments display an excellent overall performance for AEMs. The figure shows the suggested OH − transport path in AEMs.