Mechanism of proton conductivity in polyvinyl alcohol-phenolsulfonic acid membranes from 1H and 13C NMR data

Abstract

With line narrowing during magic angle spinning in solid-state NMR, molecular mobility and hydration in composite membranes based on polyvinyl alcohol (PVA) and phenol-2,4-disulfonic acid (PSA) were studied as functions of the ratio of the acidic and polymeric components, the degree of cross-linking in the polymeric matrix, and the moisture content. It is shown that at high relative humidity proton transport takes place by means of the network of hydrogen bonds, which are formed by the H+ counterions, sulfonate groups, and water molecules. At low moisture content, the hydroxyl groups in PVA play an active role in proton transport.