Silica anchored colloidal suspension of magnetite nanorods

Abstract

This study focuses on the interaction of colloidal silica nanoparticles with the magnetite (Fe3O4) magnetic fluids (MF), which eventually forms nanorod like structure. The aqueous magnetic fluid consists of magnetite nanoparticles having double layers of lauric acid surfactant. This surfactant provides stability towards short-range van der Waals attractive and steric repulsive forces, as well as long-range dipole-dipole interactive force. Whereas, in the colloidal silica, the sodium ions provide stability to the silica nanoparticles. The colloidal silica and magnetic fluid both were mixed in different proportions to understand the interaction between the silica and magnetite nanoparticles. Thus, the interaction present in the system is studied using FTIR, TGA, and magnetic field induced microscopy. The FTIR and TGA data reveal that silica interacts with the outer layer of lauric acid through the Si–O bond and eventually provides stability to the system. The length of the lauric acid sheath varies with the concentration of silica nanoparticles. The SEM images indicate nanorod formation, and its structure dimensions vary with the silica concentrations, which is also reflected in the magnetic field-induced structure formations. The structure observed using microscopy correlated with the interaction derived from FTIR and TGA data analysis. XRD data of iron oxide (magnetite) nanoparticles are present here again for completion.