Influence of nano-SiO2 on dilational viscoelasticity of liquid/air interface of cetyltrimethyl ammonium bromide

An investigation was reported on the interfacial rheology of nano-SiO2 dispersions in the presence of cetyltrimethyl ammonium bromide (CTAB). The interfacial dilational viscoelasticity had been measured as a function of the nano-particle concentration. The properties of the interface were affected by different processes such as the surfactants adsorption at the liquid or at the particle interfaces. It was found that the influence of nano-SiO2 particles on the interfacial properties was evident and complex. The property of SiO2 particles would change from hydrophilic to hydrophobic when CTAB molecules absorbed at their surface. The reorganization of surfactants and the participation of hydrophobic SiO2 at the surface were offered to explain the process. In particular, the interaction between surfactants and particles, and the transfer of particles from bulk to the surface played an important role in changing the properties of the interface.

The adsorption of SiO2 at the surface and the reorganization change the rheology of the interface film. At the appropriate concentration, the participation of SiO2 endows the interface film with more elasticity.