Particles with tunable wettability for solid-stabilized emulsions

We demonstrate that the wettability of cosmetic grade, silica-coated titanium dioxide nanoparticles may be tuned by simply soaking them in a cyclic silicone oil. This allows for tuning the type of emulsion that they stabilize, from oil-in-water to water-in-oil. By analyzing the sedimentation of water-in-oil emulsions, the effect of the soaking time (wettability) on drop size and drop-drop interactions was investigated. From centrifugation experiments performed up to emulsion breakage, we obtain an effective water-oil interfacial tension for the particle-loaded interfaces, which indicate lateral particle-particle interactions. Finally, we demonstrate that the proposed particle functionalization is terminated upon addition of water followed by emulsification. In addition, it is irreversible and can be accelerated through heating.GRAPHICAL ABSTRACT (Figure presented.).