1 Department of Chemical and Biochemical Engineering, Technical University of Denmark2 The Danish Polymer Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark3 Department of Energy Conversion and Storage, Technical University of Denmark4 Proton conductors, Department of Energy Conversion and Storage, Technical University of Denmark5 Lund University6 Lund University
Polysulfones functionalized with highly phosphonated poly(pentafluorostyrene) side chains of different lengths were synthesized applying controlled polymerization and modification methods. The graft copolymers' thermal properties were evaluated by differential scanning calorimetry and thermal gravimetrical analyses. The proton conductivity of membrane prepared from the graft copolymer with the shortest phosphonated side chains was 134 mS cm(-1) at 100 degrees C under fully immersed conditions. The graft copolymer TEM image shows a nanophase separation of ion-rich segments within the polysulfone matrix. increasing the ionic groups content in the graft copolymers led to extensive membrane swelling. To improve the dimensional stability the graft copolymers were blended with pyridine-modified polysulfone. The blend membranes were transparent with formation of nano-phase domains as revealed from TEM images. The acid-base blend membranes exhibited a slightly higher thermal stability but lower proton conductivity compared to the membranes formed from pure graft copolymers.
Journal of Membrane Science, 2014, Vol 450, p. 362-368