A new series of sulfonated cardo poly(arylene ether sulfone)s (SPES-x) with bulky and rigid side chains have been synthesized based on a novel bisphenol monomer containing electron rich tetraphenyl-methane groups. The SPES-x membranes show the desired characterizations such as high solubility in common organic solvents, good film-forming ability, excellent thermal and mechanical properties, and low methanol permeability. As ion exchange capacity (IEC) ranging from 1.61 to 2.14 mequiv g(-1), SPES-x membranes afford high conductivity (>0.08 S cm(-1)) and low swelling ratio under fully hydrated state at room temperature. Their excellent properties can be attributed to the formation of the well-defined phase-separated structures and well-connected proton transport channels observed in TEM and SAXS. Furthermore, the passive direct methanol fuel cells (DMFC) with SPES-20 membrane presents a maximum power density of 29.4 mW cm(-2) at 25 degrees C, which is superior to the value of Nafion(@) 117. (C) 2013 Elsevier B.V. All rights reserved.