Structural and Morphological Features of Perfluorosulfonic Acid Membranes Doped with Zirconium Dioxide Nanoparticles

The surface morphology, structural organization, and transport properties of composite membranes based on Russian Nafion-type perfluorinated copolymers filled with zirconium dioxide nanoparticles are studied using atomic force and scanning electron microscopy, X-ray structural analysis, and thermal analysis. A relationship between the morphology of the free surface and the “substrate” surface of Nafion-LSC-1 proton-conductive film membranes and the concentration of zirconium-dioxide nanoparticles (ZrO 2 ) is found. Atomic force and scanning electron microscopy reveals a gradient in the concentration of zirconium-dioxide nanoparticles, with the highest concentration on the substrate side of the membrane. The free surface is characterized by the presence of two phases alternating over the surface area of the membrane, which may be due to the presence of hydrophilic and hydrophobic regions. Zirconium nanoparticles form associates with sizes up to 300 nm. Wide-angle X-ray diffraction data suggest that Nafion-LSC-1 composite membranes have a mesomorphic structure when the concentration of zirconium-dioxide nanoparticles is 1.6 wt %, while the precursors of these membranes are characterized by a crystalline structure. The samples of Nafion-LSC-1 and composite membranes filled with 0.53, 1.12, and 1.61 wt % of nanoparticles are characterized by moisture content, proton conductivity, and heat resistance.