Structural Stability of Dispersions of Magnetic Nanoparticles in Aqueous Solutions of Polysorbat-80
The structural features of aggregation in magnetic fluids based on solutions of the surfactant polysorbate-80 (tween-80) were investigated. Using small-angle X-ray and neutron scattering and dynamic light scattering, the fractional distributions of magnetite and cobalt ferrite nanoparticles in a liquid carrier were obtained, for which a comparative analysis was carried out. In the case of neutron scattering, to analyze the contributions from different components of the solutions, a contrast variation based on mixtures of light and heavy water was additionally applied. As a result, it was shown that the studied systems have a more complex structure than classical magnetic fluids, when magnetic nanoparticles form “core–shell” complexes with surfactant molecules, and represent solutions of large associates (size of about 100 nm). Nevertheless, the dispersions show colloidal stability for a long (at least one year) time.