Research on the effect of different surfactants on fluidity of water-based magnetic fluid

Abstract

In order to expand the range of applications of magnetic fluid, water-based magnetic fluid with different surfactants is synthesized and the property of fluidity has been intensively studied. Three kinds of surfactants (sodium dodecyl sulfate, oleic acid and polyethylene glycol) are used to synthesize three different magnetic fluids with the same magnetic nanoparticles and carrier liquid. Their microstructures and thermal stability of magnetic nanoparticles coated with different surfactants are characterized by transmission electron microscopy and thermogravimetric analysis. Results show that water-based magnetic fluid with sodium dodecyl sulfate agglomerates more obviously while magnetic fluid with polyethylene glycol keeps good dispersion. In addition, magnetic measurements reveal that all these magnetic fluids exhibit typical superparamagnetic behavior and the magnetic fluid using polyethylene glycol as surfactant maintains the specific saturation magnetization of ∼60 emu g −1 . What is more, shear stress and viscosity of these three magnetic fluids are measured by the rotational rheometer. The shear stress increases with the increasing shear rate while the viscosity decreases with the increasing shear rate. This indicates that water-based magnetic fluid has the property of pseudoplastic fluid. What is more, the viscosity of the magnetic fluid with polyethylene glycol as surfactant is lower than other two magnetic fluids and is prone to reach a steady state at a low shear rate in a short time.

Facile Synthesis, Static, and Dynamic Magnetic Characteristics of Varying Size Double-Surfactant-Coated Mesoscopic Magnetic Nanoparticles Dispersed Stable Aqueous Magnetic Fluids

“…The prime focus of our research is on preparing stable AMF with uniformly distributed MNPs to achieve isotropic properties of the fluid. Cao et al [40] synthesized AMFs using the chemical coprecipitation method by coating three different surfactants (sodium dodecyl sulphate, oleic acid, and polyethylene glycol) to investigate the effect of different surfactants on the stability of the AMFs [40]. They confirmed from the transmission electron microscopy (TEM) results that the MNPs coated with sodium dodecyl sulphate and oleic acid showed a low stability due to agglomeration.…”

“…Furthermore, the polyethylene-glycol-coated MNPs showed a higher stability due to a lower agglomeration. However, the long-term stability and the effect of gradient magnetic field have not been probed, which are the main factors that reduce the stability of AMFs [40]. Dai et al [41] prepared the MNPs by a low-temperature freeze-drying technique followed by a coating of 3-aminopropyltriethoxysilane (APTES) on the surface to form amino-functionalized MNPs [41].…”