Creation of well-defined particle stabilized oil-in-water nanoemulsions

The preparation of oil-in-water (o/w) nanoemulsions stabilized with silica nanoparticle sols has been investigated. The emulsification was performed using a high shear homogenizer (Microfluidizer TM processor, Microfluidics, USA). The effect of different processing conditions on the droplet size distribution and stability was investigated in emulsions prepared using different types of oils, oil concentration and particle/oil ratios. It was the ability of the particles to attach to, and stabilize the newly created interface, rather than their ability to lower the interfacial tension, what proved important for the drop size of the resulting emulsions. Changes in drop size distribution with time, attributed to Ostwald ripening effects, were observed for the more soluble oils, while stable nanoemulsions with droplet size of ∼100–200 nm could be produced using a virtually water-insoluble oil such as squalene.