Quaternized poly(ether ether ketone) hydroxide exchange membranes for fuel cells

► CMPEEKs were successfully synthesized with negligible sulfonation of PEEK. ► QAPEEKOH membranes were prepared based on CMPEEK membranes. ► QAPEEKOH membranes have appropriate water uptake and moderate swelling ratio. ► QAPEEKOH membranes exhibit high hydroxide conductivity and thermal stability.