Novel physicochemical characterization of magnetic fluids

Magnetic fluids are widely used in technical and biomedical applications. Depending on the application, different properties of the magnetic fluids are of interest. In order to choose magnetic fluids for a specific application, a comprehensive characterization is needed. In this work various aqueous magnetic fluids were systematically investigated with regard to their physicochemical properties. Besides magnetic properties the chemical composition, zeta potential, core and particle size of the samples were determined. Among techniques like magnetization curve measurements or photon correlation spectroscopy novel methods like acoustic and electroacoustic spectroscopy were used, which allow size and zeta potential measurements especially in highly concentrated dispersions. Comparisons of the results obtained by the different methods show good agreements. Furthermore, the magnetic relaxation was investigated, which is of significance for a novel biomedical application. The complex requirements of magnetic fluids for this application are considered in more detail.