Magnetite/Poly(ortho-anisidine) Composite Particles and Their Electrorheological Response

• Published in: Materials Vol. 14; no. 11; p. 2900
• Main Authors: Lu, Qi, Lee, Jin-Hee, Lee, Jin Hyun, Choi, Hyoung Jin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.05.2021; MDPI
• Subjects: Acidification; core–shell; Dielectric properties; Electric field strength; Electric fields; Electrical resistivity; electro-magneto-rheological; electrorheology; Hydrocarbons; Iron oxides; Magnetic properties; Magnetism; magnetite; Nanoparticles; Newtonian fluids; Oxidation; Particulate composites; poly(o-anisidine); Polyanisidine; Polymers; Rheological properties; Rheology; Scanning electron microscopy; Silicones; Spectrum analysis; Thermogravimetric analysis; Yield stress; Japan; Germany; electro-magneto-rheological; magnetite; poly(o-anisidine); core–shell; electrorheology
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14112900

Magnetic and semiconducting Fe O /poly(o-anisidine) (POA) core/shell composite particles were fabricated by an oxidation process using Fe O synthesized separately. The dispersion stability in a liquid medium and the electrical conductivity of synthesized particles were improved because of the conductive POA polymeric shell. The morphological, microstructural, compositional/elemental, and thermal behaviors of the particles were characterized using SEM with energy dispersive X-ray spectroscopy, TEM, XRD, and thermogravimetric analysis, respectively. A smart electro-magneto-rheological suspension containing Fe O /POA particles with two functionalities, magnetism and conductivity, was prepared. Its electrorheological properties were investigated at different electric field strengths using a rotational rheometer. Without an electric field, the sample demonstrated typical Newtonian fluid behavior, as expected. However, while under the electric field, it exhibited a solid-like behavior, and the dynamic (or elastic) yield stress of the ER fluid increased linearly as a function of the electric field strength in a power-law function with an index of 2.0, following the polarization mechanism.