Title: | High concentration aqueous magnetic fluids |
Author(s): | Vasilescu, Corina ; Latikka, M. ; Knudsen, K. D. ; Garamus, V. M. ; Socoliuc, V. ; Turcu, Rodica ; Tombácz, Etelka ; Susan-Resiga, Daniela ; Ras, R. H.A. ; Vékás, L. |
Date: | 2018-01-01 |
Language: | en |
Pages: | 19 6648-6666 |
Department: | Politehnica University of Timisoara Department of Applied Physics Institute for Energy Technology Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research Romanian Academy National Institute for Research and Development of Isotopic and Molecular Technologies University of Szeged Department of Bioproducts and Biosystems |
Series: | Soft Matter, Volume 14, issue 32 |
ISSN: | 1744-683X 1744-6848 |
DOI-number: | 10.1039/c7sm02417g |
Subject: | Chemistry(all), Condensed Matter Physics, 114 Physical sciences, 221 Nanotechnology |
Keywords: | Chemistry(all), Condensed Matter Physics, 114 Physical sciences, 221 Nanotechnology |
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Vasilescu , C , Latikka , M , Knudsen , K D , Garamus , V M , Socoliuc , V , Turcu , R , Tombácz , E , Susan-Resiga , D , Ras , R H A & Vékás , L 2018 , ' High concentration aqueous magnetic fluids : structure, colloidal stability, magnetic and flow properties ' Soft Matter , vol 14 , no. 32 , pp. 6648-6666 . DOI: 10.1039/c7sm02417g |
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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.
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Description:| openaire: EC/H2020/725513/EU//SuperRepel
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