Effect of magnetic nanoparticles on the surface rheology of surfactant films at the water surface

Abstract

The stability of fluid interfaces is important in many technical fields, e.g. suspensions, emulsions and foams. In this publication we investigated the influence of maghemite nanoparticles (γ-Fe₂O₃) on the surface stability of different surfactant films (SDS, CTAB, Brij 35). We investigated the interactions between nanoparticles and surfactant films by means of surface dilatation and surface shear rheological experiments. For further characterizations we used X-ray reflectivity (XRR) measurements, dynamic light scattering (DLS) and zeta (ζ)-potential measurements. For CTAB and more obvious for SDS it was found that at low to moderate surfactant concentrations, the viscoelasticity of the interface was increased drastically in the presence of the iron oxide nanoparticles. For films of Brij 35, however, the nanoparticles did not have any influence on the surface rheology.