Poly(arylene ether ketone) Copolymer Grafted with Amine Groups Containing a Long Alkyl Chain by Chloroacetylation for Improved Alkaline Stability and Conductivity of Anion Exchange Membrane

We report simple and controllable acetylation of poly(arylene ether ketone) (PK) followed by Menshutkin reaction (quaternization), to prepare a highly alkaline stable and conductive (phase-separated) anion exchange membrane (AEM). A long side alkyl chain grafted with ammonium groups facilitates decent hydrophilic/hydrophobic microphase separation. Prepared AEMs exhibited improved conductivity, alkaline stability, and water resistivity, because of well-designed membrane architecture. Under alkaline conditions, nucleophilic substitution reaction and/or Hofmann elimination reaction (β-hydrogen) are expected to protected by grafting of a large volumetric alkyl chain (C = 16) with amine groups responsible for steric hindrance. Suitably assessed PK-QD-48 AEM reveals 0.81 V open circuit voltage (OCV) corresponding to 25.53 mW cm–2 power density at 65 °C in alkaline direct methanol fuel cell (ADMFC) operation. The reported synthetic strategy offers a novel route for preparing highly conducting, and alkaline stable, AEMs for fuel cells and diversified electrochemical applications.