High concentration aqueous magnetic fluids

structure, colloidal stability, magnetic and flow properties

Corina Vasilescu, M. Latikka, K. D. Knudsen, V. M. Garamus, V. Socoliuc, Rodica Turcu, E. Tombácz, Daniela Susan-Resiga, R. H.A. Ras, L. Vékás

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

This paper is an in-depth analysis devoted to two basic types of water based magnetic fluids (MFs), containing magnetite nanoparticles with electrostatic and with electro-steric stabilization, both obtained by chemical coprecipitation synthesis under atmospheric conditions. The two sets of magnetic fluid samples, one with citric acid (MF/CA) and the other with oleic acid (MF/OA) coated magnetic nanoparticles, respectively, achieved saturation magnetization values of 78.20 kA m−1 for the electrostatically and 48.73 kA m−1 for the electro-sterically stabilized aqueous ferrofluids which are among the highest reported to date. A comprehensive comparative analysis combining electron microscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, vibrating sample magnetometry, small-angle X-ray and neutron scattering, dynamic light scattering and magneto-rheometry revealed similarities and essential differences on the microscopic and macroscopic level between the two kinds of water-based ferrofluids. While the saturation magnetization values are quite different, the hydrodynamic volume fractions of the highest concentration MF/CA and MF/OA samples are practically the same, due to the significantly different thicknesses of the particles' coating layers. The results of volume fraction dependent structure analyses over a large concentration range by small-angle X-ray and neutron scattering, correlated with magneto-rheological investigations for the electrostatically stabilized MFs, demonstrate formation of short chains of magnetic nanoparticles which are relatively stable against coagulation with increasing concentration, while for MFs with electro-steric stabilization, magnetic field and shear rate dependent loosely bound structures are observed. These particle structures in MF/OA samples manifest themselves already at low volume fraction values, which can be attributed mainly to magnetic interactions of larger size particles, besides non-magnetic interactions mediated by excess surfactant.

Original languageEnglish
Pages (from-to)6648-6666
Number of pages19
JournalSoft Matter
Volume14
Issue number32
DOIs
Publication statusPublished - Jan 1 2018

Fingerprint

Magnetic fluids
magnetic properties
fluids
ferrofluids
Volume fraction
nanoparticles
Saturation magnetization
Neutron scattering
X ray scattering
neutron scattering
stabilization
saturation
Magnetite Nanoparticles
Stabilization
magnetization
x rays
oleic acid
citric acid
Nanoparticles
coagulation

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

Cite this

Vasilescu, C., Latikka, M., Knudsen, K. D., Garamus, V. M., Socoliuc, V., Turcu, R., ... Vékás, L. (2018). High concentration aqueous magnetic fluids: structure, colloidal stability, magnetic and flow properties. Soft Matter, 14(32), 6648-6666. https://doi.org/10.1039/c7sm02417g

High concentration aqueous magnetic fluids : structure, colloidal stability, magnetic and flow properties. / Vasilescu, Corina; Latikka, M.; Knudsen, K. D.; Garamus, V. M.; Socoliuc, V.; Turcu, Rodica; Tombácz, E.; Susan-Resiga, Daniela; Ras, R. H.A.; Vékás, L.

In: Soft Matter, Vol. 14, No. 32, 01.01.2018, p. 6648-6666.

Research output: Contribution to journalArticle

Vasilescu, C, Latikka, M, Knudsen, KD, Garamus, VM, Socoliuc, V, Turcu, R, Tombácz, E, Susan-Resiga, D, Ras, RHA & Vékás, L 2018, 'High concentration aqueous magnetic fluids: structure, colloidal stability, magnetic and flow properties', Soft Matter, vol. 14, no. 32, pp. 6648-6666. https://doi.org/10.1039/c7sm02417g
Vasilescu C, Latikka M, Knudsen KD, Garamus VM, Socoliuc V, Turcu R et al. High concentration aqueous magnetic fluids: structure, colloidal stability, magnetic and flow properties. Soft Matter. 2018 Jan 1;14(32):6648-6666. https://doi.org/10.1039/c7sm02417g
Vasilescu, Corina ; Latikka, M. ; Knudsen, K. D. ; Garamus, V. M. ; Socoliuc, V. ; Turcu, Rodica ; Tombácz, E. ; Susan-Resiga, Daniela ; Ras, R. H.A. ; Vékás, L. / High concentration aqueous magnetic fluids : structure, colloidal stability, magnetic and flow properties. In: Soft Matter. 2018 ; Vol. 14, No. 32. pp. 6648-6666.
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