The Polymer Society of Korea

Abstract

Sulfonated polystyrenes have attracted significant attention as polymer electrolytes due to their high proton conductivity. However, conventional post-sulfonation methods lead to uncertainties in acid-group concentration and substitution positions, limiting fundamental understanding of proton transport. In this study, we synthesized mono- and di-sulfonic acid polymers via controlled polymerization of monomers with precisely defined number and substitution positions of sulfonic acid groups. In di-sulfonic polymers, the spatial proximity of sulfonic acid groups induces intramolecular hydrogen bonding, thereby impacting acidity. Notably, meta- and para- disulfonic acid polystyrenes exhibited hydrophobic characteristics due to intramonomeric hydrogen-bonding interactions. Upon incorporation of ionic liquids, electrostatic interactions strongly depended on position of acid-groups, resulting in distinct ion-clustering behaviors and variation in proton conductivity and mechanical properties.