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Synthesis and Surface Modification of Deagglomerated Superparamagnetic Nanoparticles

Published online by Cambridge University Press:  10 February 2011

Christoph Lesniak ,
Thomas Schiestel ,
Riüdiger Nass  and
Helmut Schmidt
Christoph Lesniak
Affiliation:
Institut für Neue Materialien, Im Stadtwald, Geb. 43, D-66123 Saarbrülcken, Germany
Thomas Schiestel
Affiliation:
Institut für Neue Materialien, Im Stadtwald, Geb. 43, D-66123 Saarbrülcken, Germany
Riüdiger Nass
Affiliation:
Institut für Neue Materialien, Im Stadtwald, Geb. 43, D-66123 Saarbrülcken, Germany
Helmut Schmidt
Affiliation:
Institut für Neue Materialien, Im Stadtwald, Geb. 43, D-66123 Saarbrülcken, Germany
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Abstract

A method for the preparation of aminosilane coated, chemically stable, agglomerate-free superparamagnetic iron oxide nanoparticles (ferrites, e.g. Fe3O4 and γ-Fe2O3) has been developed. These nanocomposite particles posess core-shell structure. The well crystallized core particles are prepared by precipitation from aqueous salt solutions (primary particle size 10 nm). The surface modification of the weakly agglomerated core particles with aminosilane (e.g. γ-aminopropyl- triethoxysilane) leads to deagglomerated particles, covered by a thin polymerized aminosilane shell. A strong dependency of the particle/agglomerate size on the silane/iron oxideratio as well as on the disintegration time was found. A ratio of aminosilane to iron oxide of 0.8 (weight ratio) and a disintegration time of 72h result in overall particle sizes in the range of 10–15 nm. After surface modification, aminogroups are present on the particle surface (IEP of 9.5). The particles show superparamagnetic behaviour (saturation magnetization 68 EMU/g) and aqueous suspensions are stable against agglomeration. A desorption of the coating in aqueous suspensions (pH 3 to 11) is not observed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 432: Symposium S – Aqueous Chemistry and Geochemistry of Oxides , 1996 , 169
Copyright
Copyright © Materials Research Society 1997

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