Proton conductivity and methanol permeability of cellulose sulfate membranes

Abstract

We have investigated the proton conductivity, solvent uptake, and the methanol permeability coefficient (PM) in aqueous methanol solutions of the cellulose sulfate (CS) electrolyte membranes which were prepared by sulfating regenerated cellulose membranes. The proton conductivity of the CS membranes is enhanced with increasing number of sulfate groups. Solvent uptake and PM for the CS membranes are almost independent of methanol content, and the CS membranes with higher solvent uptake show higher P M. The introduction of crosslinkage into the CS membranes not only enhances the proton conductivity but also decreases the methanol permeability because of a considerable reduction in solvent uptake. The cross-linked CS membranes exhibit a proton conductivity of 0.081 S cm-1 at room temperature, which is comparable to that of Nafion 112® The methanol permeability measured by using a 3 M methanol solution is less than half, compared with Nafion 112® © 2009, The Society of Polymer Science.