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Magnetic fluids’ stability improved by oleic acid bilayer-coated structure via one-pot synthesis

Ming-Jie Chen, Hui Shen, Xin Li, Jin Ruan, and Wei-Qin Yuan

Department of Materials Science and Engineering, College of Materials and Energy, South China Agricultural University, Wu Shan Street, Guangzhou 510640, China



Abstract: To improve the magnetic fluids’ stability and demonstrate the relationships between the bilayer-coated structure and the stability, a simple method was proposed for preparingoleic acid bilayer-coated Fe3O4 magnetic fluids. The hydrophilic Fe3O4 nanoparticles coated with the bilayer-oleic acid were synthesised by a one-pot process through the chemical co-precipitation under alkaline conditions. Next, the hydrophilic Fe3O4 particles were transformed to hydrophobic particles via carboxyl-protonated modification. Carboxyl-protonated modification was found to be a reversible process, i.e. the lipophilicity of the coated Fe3O4 nanoparticles could be controlled by protonating/deprotonating the terminal carboxyl group. In addition, the space steric effect could be significantly enhanced by maximising the oleic acid adsorption and increasing the thickness of the coated layer, resulting in the oleic acid bilayer-coated Fe3O4 nanoparticles exhibiting better performance in the stability of the hexanemagnetic fluids than oleic acid monolayer-coated Fe3O4 nanoparticles.

Keywords: protonated modification; Fe3O4 nanoparticles; oleic acid; bilayer-coated structure; hexane magnetic fluids

Full paper is available at

DOI: 10.1515/chempap-2016-0096


Chemical Papers 70 (12) 1642–1648 (2016)

Saturday, July 04, 2020

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