Composite Perfluorinated Membranes Modified by Polyvinyl Alcohol Cross-Linked with Sulfosuccinic Acid

The effect of polyvinyl alcohol (PVA) cross-linked with sulfosuccinic acid on the structure, morphology, physical, mechanical and electrochemical properties of composite membranes made of domestic perfluorinated copolymer, an analogue of Nafion, and PVA was studied. An increase in the amount of cross-linked PVA in the membrane leads to an increase in proton conductivity. The crystallinity of the composites depends on the proportion of the cross-linking agent. The morphology of the membrane surfaces varies significantly: the lower surface has a uniform microstructure, and the upper surface forms three-dimensional folded structures during self-organization of polymer chains in the surface layer. According to energy-dispersive analysis, the two layers of the membrane differ significantly in chemical composition, which is illustrated by the distribution profiles of fluorine across the membrane thickness. The observed structural and morphological features of the membranes explain the differences in their proton conductivity.