A novel strategy was proposed to construct a bicontinuous hydrophilic/hydrophobic micro phase separation structure which is crucial for high hydroxide conductivity and good dimensional stability anion exchange membranes (AEMs). A semi-flexible poly (aryl ether sulfone) containing a flexible aliphatic chain in the polymer backbone with imidazolium cationic group was synthesized by the polycondensation of bis(4-fluorophenyl) sulfone and the self-synthesized 4,4'-[butane-1,4-diylbis(oxy)] diphenol followed by a two-step functionalization. The corresponding membranes were prepared by solution casting. More continuous hydroxide conducting channels were formed in the semi-flexible polymer membranes compared with the rigid based ones as demonstrated by TEM. As a result, given the same swelling ratio, hydroxide conductivity of the semi-flexible polymer membrane was about 2-fold higher than the one of the rigid polymer based membrane (e.g., 45 vs. 22 mS cm(-1) with the same swelling ratio of 24% at 20 degrees C). The highest achieved conductivity for the semi-flexible polymer membranes at 60 degrees C was 93 mS cm(-1), which was much higher those of other random poly (aryl ether sulfone) based imidazolium AEMs (27 -81 mS cm(-1)). The single cell employing the semi-flexible polymer membrane exhibited a maximum power density of 125 mW cm(-2) which was also higher than those for other random poly (aryl ether sulfone) based imidazolium AEMs (16-105.2 mW cm(-2)). (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.