Transport properties of sulfonated poly (styrene-b-isobutylene-b-styrene) triblock copolymers at high ion-exchange capacities Academic Article uri icon


  • Transport properties of sulfonated poly(styrene-b-isobutylene-b-styrene) (S-SIBS) triblock copolymers were examined as a function of ion-exchange capacity (IEC), specifically at high lECs (up to 2 mequiv/g). The proton conductivity of S-SIBS was 1 order of magnitude higher than sulfonated polystyrene at similar IECs and 3-fold higher than Nafion 117 at an IEC of 2 mequiv/g. However, all polymers in this study possessed similar selectivities (i.e., proton conductivity/methanol permeability) regardless of chemistry or morphology. Small-angle X-ray scattering reveals a periodic-to-nonperiodic transition in S-SIBS with an anisotropic lamellar morphology oriented in the plane of the membrane at IECs ranging from 0.5 to 1 mequiv/g and an isotropic cocontinuous morphology at IECs ranging from 1.1 to 2 mequiv/g. This morphological transition coincides with a discontinuity in the IEC-dependent transport properties. In addition, S-SIBS transport properties were measured after solution casting from 15 different solvents at a constant IEC (0.8 mequiv/g). Transport properties varied by almost 3 orders of magnitude when comparing S-SIBS solution cast from toluene to a toluene/ethanol mixture. X-ray scattering results show morphological differences with solvent choice. This study demonstrates the significant impact of morphology on transport properties in ionic block copolymers. 2006 American Chemical Society.

published proceedings


altmetric score

  • 6

author list (cited authors)

  • Elabd, Y. A., Napadensky, E., Walker, C. W., & Winey, K. I.

citation count

  • 162

complete list of authors

  • Elabd, YA||Napadensky, E||Walker, CW||Winey, KI

publication date

  • January 2006