Investigation of the magnetic properties of ionic liquid-based ferrofluids

Pierfrancesco Maltoni presents our latest Ionic-liquid (ILs) based ferrofluids results in Pisa. ILs have emerged as versatile solvents due to their tunable physicochemical properties, which make them ideal for applications in materials science and nanotechnology. This study introduces a novel method for dispersing single-domain spinel ferrite magnetic nanoparticles (MNPs) directly into an ionic liquid, 3-ethyl-1-methylimidazolium acetate (EMIMAc), without water contamination. MNPs with different chemical compositions (γ-Fe₂O₃, Co₀.₅Zn₀.₅Fe₂O₄, and CoFe₂O₄) were synthesized via the polyol method, achieving uniform particle size (~5 nm) and tunable magnetic properties. The particles were coated with dihydrocaffeic acid (DHCA) in tetrahydrofuran to ensure stability and compatibility with EMIMAc.

Direct (water-free) and indirect (water-involving) dispersion methods were compared, revealing that both approaches yield stable IL-based ferrofluids (IL-FFs) with minimal differences in aggregation or size distribution [3]. Magnetic characterization showed that dispersion in ILs modulates the interparticle interactions and magnetic anisotropy, with cobalt doping enhancing magnetic anisotropy due to strong Co²⁺ single-ion contributions. Additionally, the study highlights how the interplay between interparticle interactions and magnetic anisotropy impacts magnetization dynamics, offering insights into tailoring IL-FFs for advanced applications.