(372f) Synthesis of Surfactant Bilayer Coated Iron Oxide Nanoparticles for the Stabilization of Oil-in-Water Emulsions

Magnetic nanoparticles have highly tunable physicochemical properties which are extremely important in applications like catalysis, biomedicine, environmental remediation and data storage. Significant interfacial properties resulting from their small size can be used in stabilizing oil-in-water Pickering emulsions by making the nanoparticles adsorb at the surface of the oil droplet in water. Nanoparticle (NP)-stabilized Pickering emulsions offer various opportunities to create oil-in-water emulsions. The objective of this work is to investigate the effect of the primary particle characteristics and stabilizing agent chemistry on the stability of oil-in-water Pickering emulsions. Iron oxide nanoparticles were synthesized by the co-precipitation method using stoichiometric amounts of Fe²⁺ and Fe³⁺ salts and ammonium hydroxide. These particles were then coated with bilayers of fatty acids, FDA approved emulsifiers and other benign compounds and subsequently dispersed in aqueous and organic solvents depending upon their nature. Generation of a monolayer or a bilayer coating on the nanoparticles was also controlled through systematic changes in reagent amounts. Characterizations of these nanoparticles were performed through the use of transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier Transform Infrared spectroscopy (FTIR) to analyze their size distribution and ligand-solvent interactions.

In this study, using a control test-system of n-dodecane (organic phase) and aqueous phases of various pH values, the capacity of these bilayer coated nanoparticles to stabilize oil-in-water emulsions was also systematically determined. The stability of these emulsions with respect to creaming and particle precipitation was studied using visual methods like optical microscopy and techniques such as Zeta-potential analysis. The oxidation state of these particles was also characterized using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD).