Metal nanoparticle fluids with magnetically induced electrical switching properties

Abstract

We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (Au_NPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (M_w) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH–Au_NPs) were prepared by the addition of FeCl₃ powder to metal fluids (i.e., IL-SH–Au_NPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high M_w. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media.