Title

Effects of Fatty Acid Surfactants on the Magnetic and Magnetohydrodynamic Properties of Ferrofluids

Document Type

Article

Publication Date

12-1-2009

Publication Title

Journal of Applied Physics

Abstract

We prepared Fe 3 O 4 magnetic nanoparticles having diameters of approximately 12 nm by chemical coprecipitation, which were coated with three different fatty acid surfactants: oleic acid, lauric acid, and myristic acid. From x-ray diffraction, transmission electron microscopy, and Mössbauer spectroscopy measurements we confirmed that Fe 3 O 4 is the only phase present in the samples. The zero field cooled magnetization curves for the nanoparticles exhibit broad peaks, consistent with superparamagnetic blocking for the polydisperse samples, and a saturation magnetization smaller than that for bulk Fe 3 O 4 . Although there are minimal differences in the magnetic properties of the nanoparticles having different surfactants, we find significant changes in the hydrodynamic response depending on chain length. Hyperthermia measurements show considerably larger response for oleic acid-coated samples, while magneto-optical studies indicate that these samples have slower dynamics of aggregation under the influence of a dc field. These results suggest that the magnetohydrodynamic response of ferrofluids can be controlled by judiciously selecting appropriate surfactants.

Volume

106

Issue

11

First Page

1

Last Page

9

DOI

https://doi.org/10.1063/1.3259382

ISSN

0021-8979

Comments

ESSN: 1089-7550

Rights Statement

© 2009 American Institute of Physics.

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