IR Study of a Polymer Proton-Conducting Electrolyte Based on Poly(vinyl alcohol) and Phenol-2,4-Disulfonic Acid

The structure and hydration of phenol-2,4-disulfonic acid in the individual state and in the system with poly(vinyl alcohol) at low and high humidity levels are studied by IR spectroscopy. It is shown that all characteristic features of the electrolytic dissociation of phenol-2,4-disulfonic acid via proton transfer from acid molecules to the molecules of water in the liquid phase of the binary system phenol-2,4-disulfonic acid–water are also observed for the viscous solutions of the triple system poly(vinyl alcohol)–phenol-2,4-disulfonic acid–water, although differences make themselves evident if water molecules are in deficiency. It is found that evacuation of the phenol-2,4-disulfonic acid film for several hours at room temperature leads to its dehydration and eventually causes formation of molecular dimers [C6H3OH(SO2OH)2]2. A similar operation with the poly(vinyl alcohol)–phenol-2,4-disulfonic acid film is completed by the transfer of a proton from the acid molecule to the–ОН group of poly(vinyl alcohol) according to the following scheme: nC6H3OH(SO2OH)2 + (–CH2OH) n → nC6H3OH(SO3)(SO2OH)– + (–CH2OH2) n + .