Rigid crosslinkers towards constructing highly-efficient ion transport channels in anion exchange membranes

Abstract

Synthetic anion exchange membranes (AEMs) usually suffer from low conductivity, bad alkaline stability and poor dimensional stability. Constructing efficient ion transport channels is considered to be one of the most effective ways for preparing the AEMs with the high conductivity and low swelling ratio. Herein we demonstrate a facile strategy to achieve this goal via using the rigid crosslinkers to expend the interchain spacing of polymer chains. Three crosslinkers are chose to modify poly (ether ketone) (PEK) AEMs. The AEMs with rigid crosslinkers have more efficient ion transport channels and thus show both higher water uptake and higher ionic conductivity, compared with the AEM with the flexible crosslinker. Especially, the hydroxide conductivity of the AEM increases from 63.2 to 110.3 mS cm−1 at 80 °C when the short flexible crosslinker is replaced by the long rigid crosslinker. Meanwhile, the swelling ratios (SR) are less than 25%. The rigid crosslinkers should be beneficial to construct efficient ion channel and overcome the trade-off relation between the ionic conductivity and dimensional stability of the synthetic AEMs.