Structure-Property Relationship of Aluminum-Neutralized Sulfonated Styrenic Pentablock Copolymer

We report the effects of aluminum neutralization on the morphology, water sorption, mechanical properties, water and ion transport properties, and free volume of a symmetric styrenic pentablock copolymer. The primary spacing, as measured by SAXS, decreased upon aluminum neutralization, and the primary feature spacing increased as the polymer absorbed water. Aluminum neutralization produced a stronger hydrated polymer compared to the hydrated non-neutralized polymer. The dry aluminum-neutralized polymer was more brittle than the non-neutralized polymer. The polymer’s free volume element size decreased upon aluminum neutralization, and the free volume element size depended on water uptake.  Aluminum neutralization of the polymer’s sulfonate groups resulted in a 5.5-fold decrease of water uptake. An additional effect of the aluminum neutralization process was a decrease in the sensitivity of sodium chloride permeability to salt concentration, consistent with Donnan exclusion theory.


G. M. Geise, C. L. Willis, C. M. Doherty, A. J. Hill, T. J. Bastow, T. J. Ford, K. I. Winey, B. D. Freeman, D. R. Paul*, Industrial & Engineering Chemistry Research, 52 (3), 1056–1068. 2013.
“Characterization of aluminum-neutralized sulfonated styrenic pentablock copolymer films.”