Poly(arylene ketone) based electrolyte membranes composed of hydrophilic-hydrophobic block segments were prepared for fuel cell application. 4,4'-bis(4-hydroxyphenyl)-valeric acid and 4,4'-difluorobenzophenone monomers were used for the synthesis of hydrophobic oligomers and bisphenol A and 4,4'-difluorobenzophenone for the hydrophobic ones. The proton conductivity was provided by the sulfonation of the pendant carboxylic groups in hydrophilic block. Chemical structure of oligomers and polymer were identified using NMR and GPC. Development of defined hydrophobic-hydrophilic phase separation was assured by SAXS and AFM and TEM spectroscopies. While the thermal, mechanical and chemical stabilities were endowed from the hydrophobic blocks, proton conduction and water uptake properties by hydrophilic blocks. The proton conductivity and water uptake increased with increasing length of the hydrophilic block. The proton conductivity was comparable to Nafion 117 membrane at the hydrophobic-hydrophilic block length ratio of . still maintaining low water uptake of %. Ion clusters of the block copolymers were observed by SAXS.
