Novel Formulation of Ionic Liquid-Based Ferrofluids: Investigation of the Magnetic Properties

: This study establishes a viable process to prepare hybrid nanomaterials comprising stable ionic liquid-based ferrofluids (IL-FFs) with tunable magnetic anisotropy and reduced water contamination, where the latter strongly decreases the colloidal stability of the system. Spinel iron oxide magnetic nanoparticles (MNPs) with different compositions (γ-Fe2O3, Co0.5Zn0.5Fe2O4, and CoFe2O4) and different magnetic anisotropies were synthesized by the polyol method. The particles were coated with dihydrocaffeic acid (DHCA) in tetrahydrofuran (THF) and subsequently transferred directly to 3-ethyl-1-methylimidazolium acetate (EMIMAc), exploring the synergy between intermolecular and covalent bonding to obtain stable dispersions. The evolution of magnetic properties from powder to IL-FFs systems was investigated, allowing us to highlight the synergistic influence of interparticle interaction and magnetic anisotropy on the magnetization dynamics of the nanoparticles.