Structural Organization of Magnetic Fluids Stabilized with Fatty Acids

Лысенко, С. Н.; Derechi, K. V.; Астафьева, С. А.; Yakusheva, D. E.

doi:10.1134/s2075113318020193

Cited by 2 publications

(4 citation statements)

References 10 publications

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“…Recently the authors have established some regularities and mechanism of particle stabilization in magnetic colloids [37]. In addition, the structure of the surface layer has been described [28]. In present work the mechanism of particle stabilization is not clear enough due to some contradictory data, obtained using SAXS and SANS methods.…”

Section: Ferrofluidmentioning

confidence: 83%

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Preparation and magneto-optical behavior of ferrofluids with anisometric particles

et al. 2020

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Nanoparticles of barium hexaferrite have been synthesized by hydrothermal method. Copper and cobalt ferrite nanoparticles have been prepared via a novel coprecipitation technique. The particles were characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering, magnetic granulometry, wide angle x-ray diffraction, small angle x-ray scattering, small angle neutron scattering. For preparation of the ferrofluids, relatively large nanoplates have been stabilized by a double layer. A stabilization method has been developed and the stable ferrofluids with large particles have been obtained. Magneto-optical effects in the ferrofluids containing both spherical and anisometric ferrite nanoparticles have been studied. The ferrofluids with relatively large nanoplates—61 and 51 nm—have been found to be efficient magneto-optical media. Magneto-optical response in these media has been shown to be one or two orders of magnitude higher, than the one in the colloids with particle size about 10 nm. Characteristic frequencies and aggregate sizes have been determined using experimental data.

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Section: Ferrofluidmentioning

confidence: 83%

“…The particle size of cobalt ferrite, determined from magnetization curve, was about 9 nm. Unlike DLS, in this method the size of magnetic core is determined, and for hydrodynamic particle size the stabilizing layer thickness can be calculated [28] from atomic bonds given in reference books.…”

Section: Characterization Of Nanoparticlesmentioning

confidence: 99%

Preparation and magneto-optical behavior of ferrofluids with anisometric particles

et al. 2020

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“…Meanwhile, for the thinner stabilizing layers, new effects associated with the steric interactions between the surfactant and solvent molecules can be observed. The point is that thin protective layers are very dense and almost do not overlap . If the solvent molecules are large enough, they cannot penetrate inside the stabilizer layer.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The point is that thin protective layers are very dense and almost do not overlap. 56 If the solvent molecules are large enough, they cannot penetrate inside the stabilizer layer. As a result, a good solvent acquires precipitative properties as was shown experimentally in refs 25−27.…”

Section: S E C O N D T H E R a T I Omentioning

confidence: 99%

Osmotic Attraction: A New Mechanism of Nanoparticle Aggregation

et al. 2022

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Solvent-induced interactions of nanoparticles in colloidal solutions can substantially affect their physicochemical and transport properties. Predicting these interactions is challenging because the natural causes of the interactions are unclear. Here, we present a comprehensive experimental and theoretical study of the coagulation stability of the surfacted magnetic colloids. The magnetite nanoparticles stabilized by erucic acid were dispersed in 19 different good solvents. The colloidal stability was reduced by the gradual addition of a precipitant. As a precipitant, 19 other liquids were used. We show that coagulation is not associated with either dispersion or magnetic interactions. The coagulation mechanism is due to the osmotic attraction of nanoparticles induced by a specific local distribution of precipitant molecules. The precipitant molecules are repelled from the hydrophobic tails of the surfactant and form a depleted zone inside the surfactant layer leading to the appearance of the osmotic attraction between the nanoparticles and their subsequent coagulation when the critical concentration of the precipitant is reached. The quantitative description of the phenomenon is carried out within the framework of the generalized Asakura–Oosawa model of the attractive depletion forces between two adjacent particles and the Langmuir adsorption model for the equilibrium concentration of precipitant molecules in the surfactant layer of nanoparticles. The calculated precipitant critical concentrations, the coagulation curves of the polydisperse systems, and the variation of the coagulation criterion occurring upon changing the surfactant are in good agreement with the experimental data. The osmotic attraction mechanism is equally suitable for nanoparticles of any natureplasmonic, semiconductor, or magnetic. This is determined by the surfactant–solvent interactions and is generic for many solvent-mediated systems taken at arbitrary concentrations of precipitant.

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Structural Organization of Magnetic Fluids Stabilized with Fatty Acids

Cited by 2 publications

References 10 publications

Preparation and magneto-optical behavior of ferrofluids with anisometric particles

Preparation and magneto-optical behavior of ferrofluids with anisometric particles

Osmotic Attraction: A New Mechanism of Nanoparticle Aggregation

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