Side-chain-type poly(arylene ether sulfone)s containing multiple quaternary ammonium groups as anion exchange membranes

A new difluorodiphenyl sulfuric monomer, 3,3',5,5'-tetra(3 '',5 ''- dimethylphenyl)-4,4'-difluorucliphenyl sullone (NI-DFDPS), was synthesized and further polymerized to form a series of poly(arylene ether sullone)s containing four pendent 3,5-dimethylphenyl groups. After bromination of benzylmethyl groups, side-chain-type poly(arylene ether sullone)s containing multiple quaternary ammonium groups in pendant phenyl rings (PAES-Q-xx) were prepared by quatemization. Their chemical structures and some properties, including water uptake, swelling ratio, hydroxide conductivities, and thermal and alkaline stabilities, were investigated. These PAES-Q-xx membranes with IEC values of 1.65-2.36 mequivig had low water uptake and swelling ratio. Their conductivities were all above 10 mS/cm and the values were in the range of 23-37 and 54-82 mS/cm at 20 and 80 degrees C, respectively. The good conductivity is probably due to the high IEC and the dense distribution of the pendant quaternary ammonium groups. In addition, PAES-Q-xx membranes also displayed good thermal and alkaline stabilities. (C) 2015 Elsevier B.V. All rights reserved.