Bidisperse colloids: Nanoparticles and microemulsions in coexistence

Mixed ‘hard–soft’ colloidal systems have been generated in which the ‘hard’ components (80 nm diameter silica nanoparticles) coexist with a population of ‘soft’ microemulsion droplets, both structures stabilised by the anionic surfactant sodium bis(ethylhexyl)sulfosuccinate (AOT) with toluene as solvent. The addition of water to swell the inverse micelles to form microemulsion droplets appears to increase attractive interactions between the silica particles (determined by DLS), possibly due to adsorption of some water at the silica–toluene interface; however, long-term stability of the dispersions is maintained. Small-angle neutron scattering was used to examine the structures present in these new colloidal systems.

Schematic and neutron contrast conditions showing microemulsion droplets in coexistence with large (∼80 nm) silica nanoparticles stabilised by a layer of anionic surfactant in toluene.Figure optionsDownload high-quality image (63 K)Download as PowerPoint slide