Synthesis of Polymer Electrolyte Membranes from Sulfonated Poly(Arylene Ether Ketones) with Partial Substitution of Carboxylate Acid Group

Abstract

Chemical modification of Sulfonated poly(arylene ether ketone) with carboxylate acid side chain (C-SPAEK) membranes has been conducted through partially substitution of the 4,4-bis(4hydroxyphenyl)-valeric acid (DPA) with 4,4-bis(4-hydroxyphenyl)-propane (BPA) at varies different compositions of sulfonate. FTIR and EDS analysis of the synthesized SPAEK revealed the presence of carboxylic acid, methyl, sulfonate groups and aromatic ether bonds in the SPAEK membrane. The effect of different compositions of carboxylic acid and sulfonate groups on mechanical strength, thermal stability, oxidative stability, water absorption, swelling ratio and proton conductivity of the membranes was studied. The SPAEK-50/50 membrane exhibits superior properties with high mechanical strength, high thermal and oxidative stability, good water absorption, low swelling ratio, high dimensional stability and has a proton conductivity at 80 °C of 0.102 S/cm close to the Nafion-117 membrane of 0.120 S/cm. This finding confirms that the partial substitution of the hydrophilic monomer of DPA with 50 % mole of BPA with a sulfonate group composition of 50 % resulted in an excellent SPAEK membrane.