Research Center for Engineering of
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Title: Comparative analysis of structure of polar ferrofluids by small-angle neutron scattering
Published In: Journal of Colloid and Interface Science, Vol. 295, No. 1, pp. 100-107
Description: Results of experiments on small-angle neutron scattering from ferrofluids on polar carriers (pentanol, water, methyl-ethyl-ketone), with double-layer sterical stabilization of magnetic nanoparticles, are reported. Several types of spatial structural organization are observed. The structure of highly stable pentanol-based samples is similar to that of stable ferrofluids based on organic non-polar carriers (e.g., benzene) with mono-layer covered magnetic nanoparticles. At the same time, the effect of the interparticle interaction on the scattering is stronger in polar ferrofluids because of the structural difference in the surfactant shell. The structure of the studied methyl-ethyl-ketone- and water-based ferrofluids essentially different from the previous case. The formation of large (> 100 nm in size) elongated or fractal aggregates, respectively, is detected even in the absence of external magnetic field, which corresponds to weaker stability of these types of ferrofluids. The structure of the fractal aggregates in water-based ferrofluids does not depend on the particle concentration, but it is sensitive to temperature. A temperature increase results in a decrease in their fractal dimension reflecting destruction of the aggregates. In addition, in water-based ferrofluids these aggregates consist of small (radius similar to 10 nm) and temperature-stable primary aggregates.
ISSN:ISSN: 0021-9797
DOI:DOI: 10.1016/j.jcis.2005.07.048
Publication year: 2006
Keywords:ferrofluids; magnetic fluids; sterical stabilization; small-angle neutron scattering; aggregation
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Authors: AVDEEV Mikhail , AKSENOV Viktor Lazarevich , BALASOIU Maria , GARAMUS Vasil , SCHREYER Andreas , TOROK Gyula , ROSTA Laszlo , BICA Doina , VEKAS Ladislau ,
Type: International Journal Article
Laboratory: Magnetometry Laboratory
Institution: ARFT