Water Uptake and Proton Conductivity of Asymmetric Poly(styrenesulfonate-block-methylbutylene) Copolymers

The effect of chain architecture on water uptake and proton conductivity of poly(styrenesulfonate-block-methylbutylene) (PSS-PMB) copolymers at equilibrium with moist air is studied as a function of temperature, and relative humidity of the air. Symmetric and asymmetric PSS-PMB copolymers were synthesized by anionic polymerization of poly(styrene-block- isoprene) copolymers, followed by hydrogenation of the polyisoprene block and sulfonation of the polystyrene block. Previous studies have shown that symmetric PSS-PMB block copolymers in the presence of humid air (relative humidity$>$50\%) are excellent proton conductors at temperatures as high 90 C. Current work is focused on water uptake and conductivity measurements on asymmetric PSS-PMB block copolymers with PSS as the minor component.