Block poly(arylene ether nitrile ketone)s with comb-shaped alkyl chains as anion exchange membranes

A new approach is presented here for constructing higher-performance anion exchange membranes (AEMs) by combining block-type and comb-shaped architectures. A series of quaternization fluorene-containing block poly (arylene ether nitrile ketone)s (QFPENK-m-n) were synthesized by varying the length of hydrophobic segment as AEMs. The well-designed architecture, which involved grafting comb-shaped C10 long alkyl side chains onto the block-type main chains, formed efficient ion-transport channels, as confirmed by atomic force microscopy. As a result, the AEMs showed high hydroxide conductivities in the range of 34.3–102.1 mS⋅cm−1 from 30 to 80 °C at moderate ion exchange capacities (IECs). Moreover, the hydrophobic segment with nitrile groups also exhibited a profound anti-swelling property for the AEMs, resulting in ultralow swelling ratios ranging from 4.7% to 7.1% at 30 °C and 7.5%–9.8% at 80 °C, as well as superb conductivity-to-swelling ratios at 80 °C. In addition, the AEMs displayed good mechanical properties, thermal and oxidative stability, and optimizable alkaline stability.