Dual Electrorheological and Magnetorheological Behaviors of Poly(N-methyl aniline) Coated ZnFe2O4 Composite Particles

Abstract

Magnetic/conducting polymeric hybrid core-shell typed zinc ferrite (ZnFe2O4)/poly(N-methyl aniline) (PMA) particles were fabricated and adopted as electrorheological (ER) and magnetorheological (MR) fluids, and their rheological properties were examined. Solvo-thermally synthesized ZnFe2O4 was coated with a conducting PMA through chemical oxidation polymerization. The size, shape, and chemical composition of the final core-shell shaped particles were scrutinized by scanning electron microscopy, transmission electron microscopy, and Fourier transform-infrared spectroscopy. The crystal faces of the particles before and after coating with PMA were analyzed by X-ray diffraction. The ZnFe2O4/PMA products were suspended in silicone oil to investigate the rheological response to electro- or magnetic stimuli using a rotating rheometer. The shear stresses were analyzed using the CCJ equation. The dynamic yield stress curve was suitable for the conductivity mechanism with a slope of 1.5. When magnetic fields of various intensities were applied, the flow curve was analyzed using the Hershel–Bulkley equation, and the yield stresses had a slope of 1.5. Optical microscopy further showed that the particles dispersed in insulating medium form chain structures under electric and magnetic fields. Via this core-shell fabrication process, not only spherical conducting particles were obtained but also their dual ER and MR responses were demonstrated for their wide potential applications.

Recent Developments in the Use of Polyaniline-Based Materials for Electric and Magnetic Field Responsive Smart Fluids

“…In another study, rough surfaces were observed when ZnFe 2 O 4 was coated with dedoped-PAn with dual-field responsive properties [123]. Also, PAn derivatives poly(N-methyl aniline) [124] and poly (diphenylamine) [125] were also reported to be as a shell layer on magnetic ZnFe 2 O 4 particles without any requirement of an additional de-doping process. PAn-coated spherical MnFe 2 O 4 nanoparticles were reported with dual characteristics of ER/MR fluids [127].…”

Morphology-controlled stabilised polyaniline nanoparticles and their electrorheological properties

“…However, polyaniline (PANI) is one of the most studied conducting polymers, due to its particularly good stability and multiple oxidation states. Some notable ER studies on PANI and its derivatives include coatings of the polymers on nanoparticles of carbon, 8 TiO 2 , 9 clays, 10 zeolites, 11 magnetic oxides 12 and graphene oxide, 13 as well as surfactant-stabilised polymer nanostructures. 14 This field has recently been well reviewed.…”

A Novel Magnetorheological Fluid with High-Temperature Resistance

“…Magnetorheological (MR) materials are a significant branch of intelligent materials which make continuous and nonpolar reversible changes under the action of a magnetic field. MR fluids mainly comprise soft magnetic particles, surfactants, and the base carrier fluid [ 1 , 2 , 3 , 4 , 5 ]. Among these, the magnetic properties of soft magnetic particles are the main reason for the unique rheological effect of MR fluids.…”

“…Furthermore, the high-temperature oxidation properties of soft magnetic particles also directly influence transmission factors such as flow characteristics, sedimentation stability, and the shear yield stress of MR fluids. The base carrier fluid type has an important influence on performance indexes such as the working temperature and zero-field viscosity of MR fluids [ 2 ].…”