In order to improve the performance of anion exchange membrane (AEMs) as the core component of alkaline fuel cell, a novel pentamethyl-contained phenolphthalein multiarm monomer is synthesized. The highly imidazolium-functionalized poly (arylene ether ketone) membrane (Im-PEK-x) are prepared by introducing 1,2-dimethylimidazole as hydrophilic segments. The monomer, polymer and anion exchange membranes are confirmed by H-1 NMR spectra. The well-defined micro-phase separated structure of membranes is conducive to ion transport and the structure is investigated by TEM and SAXS. The imidazolium-functionalized membranes (Im-PEK-0.8) exhibits high ionic conductivity (0.148 S/cm at 80 degrees C). The tensile strength of Im-PEK-0.8 membrane is 30.06 MPa. Furthermore, after immersing in 60 degrees C, 2 M NaOH solution for 240 h, the ionic conductivity remains 0.092 S/cm for Im-PEK-0.8. The 1,2-dimethylimidazole enhance alkaline stability by steric effect of the substituent group at the C2 position. All these results indicate that this is a new method to enhance conductivity and stability performance of AEMs. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.