Gadolinium oxide-decorated graphene oxide-based dual-stimuli-responsive smart fluids

Gadolinium and its compounds have attracted attention for application in various fields owing to their dielectric and magnetic properties; however, using gadolinium compounds has not yet been reported in the field of smart fluids. Herein, gadolinium oxide (Gd₂O₃)-based composites were used to develop dual-stimuli-responsive smart fluids. The resulting Gd₂O₃ nanoparticle (NP)-decorated graphene oxide (Gd₂O₃/GO) composites responded to external electric and magnetic fields due to the presence of GO and Gd₂O₃, respectively. The rheological properties of the electro-magneto-rheological (EMR) fluids under electric and magnetic fields were subsequently investigated. The magnetic response of the EMR fluids was enhanced with increasing Gd₂O₃ content; however, the electric response was reduced. Thus, the Gd₂O₃ content of the composites played an important role in the rheological properties of the EMR fluids. The electro- and magneto-responsive properties of the composite material were tunable owing to the instability of the electrostatic interactions between the composite particles. Moreover, the fabricated EMR fluids exhibited a higher dispersion stability than the GO-based electro-rheological fluid because of the hydrophobic oleic acid coating on the Gd₂O₃ NPs. This study demonstrates the potential of expanding the material selection for developing smart fluid systems.