Comb-shaped block poly(arylene ether sulfone ketone)s for anion exchange membranes

Abstract

A well-designed architecture is presented here to construct high-performance anion exchange membranes (AEMs). A series of quaternized fluorene-containing block poly(arylene ether sulfone ketone)s (QFPESK-m-n) is synthesized as the main chains, and grafted with comb-shaped C8 long alkyl chains for the AEMs. By varying the hydrophilic segment’ length, there has been a significant change in the microstructure as well as phase separation morphology of the membranes, as confirmed by atomic force microscopy. Hence the as-prepared AEMs with moderate ion exchange capacities (IECs) show enhanced hydroxide conductivities in the range of 28.8―94.7 mS⋅cm−1 from 30 to 80°C. Furthermore, based on the block backbones and hydrophobic comb-shaped alkyl chains, the AEMs show low-level swelling ratios of 4.3% to 9.2% at 30°C and from 6.2% to 13.2% at 80°C, and superior ratios of conductivity to swelling. In addition, the QFPESK-m-n AEMs also depict acceptable mechanical properties, good thermal stability and an optimizable alkaline stability.