Dilational rheology of spread and adsorbed layers of silica nanoparticles at the liquid-gas interface

This short review is devoted to recent achievements in studies of the dilational surface rheological properties of the systems containing complexes of silica nanoparticles with conventional surfactants. It is shown that there is a surfactant concentration range where the dynamic surface elasticity reaches extremely high values up to 1000 mN/m. This result can explain the formation of very stable foams and emulsions con taining nanoparticles. In some surfactant concentration ranges the adsorption layer is characterized by a non linear response to small compressions or expansions of the liquid surface. Possible causes of this behavior and the mechanism of main relaxation processes are briefly discussed.