Highly Fluorinated Sulfonated Poly(arylene ether sulfone) Copolymers: Synthesis and Evaluation of Proton Exchange Membrane Properties

This article reports the synthesis and characterization of several new fluorinated sulfonated poly(arylene ether sulfone) (6FBPAQSH-XX). The structures of the prepared copolymers were confirmed by FTIR and NMR spectroscopy. The copolymers showed high molecular weight, good solubility, and film-forming capabilities. The copolymers exhibited high thermal and oxidative stability and good mechanical properties depending upon their chemical compositions. Transmission electron microscopy (TEM) showed cluster like microstructures for the copolymer membranes suggesting good phase separated morphology. The cluster size increased with increasing mole percentage of sulfonate comonomer and was in the range of 5-65 nm. The copolymers showed good dimensional stability with very low water uptake and swelling ratios. Ion exchange capacity (IECw) of the copolymer films was determined by titration methods and was also calculated from the monomer composition obtained by H-1 NMR spectroscopy. The proton conductivities of acid form membrane increased with IECw value and temperature, with maximum to 108 mS/cm at 90 degrees C for 6FBPAQSH-60 copolymer.