Characterization of Polyelectrolyte Membranes with in-Situ Metal-Oxide Nanoparticles

The in-situ growth of metal-oxide nanoparticles (MONP) in polyelectrolyte membranes (PEM), Nafion 117, has been investigated. Among several potential applications, such as fuel cells, water purification, and others, these PEM can serve as self-detoxifying composite PEM barriers against dangerous organic compounds, such as chemical warfare agents. These PEM have interconnected hydrophilic and hydrophobic sub-domains, which can serve as perm-selective barriers. In-situ formation of MONP within PEM occurs at the interconnected hydrophilic sub-domains in which the sulfonated groups are present and the ion exchange occurs. Ion exchange capacities of these hydrophilic sub-domains have been studied with mono-, di-, and tri-valent ions to estimate theoretical MONP particle loading within membranes. After MONP growth, water uptake, membrane porosity, fixed ion concentration, hydration number, and a series of other experiments were studied to assess the impact of MONP formation in membrane mechanical and transport properties. Techniques used for the characterization of PEM and MONP include x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and complexometric titrations.