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Weiche Materie Poster: Do., 13:00–15:30 D-P357
SANSPOL study of organic magnetic fluids stabilized by different monocarboxylic
acids
Ladislau Vekas 1 , Mikhail V. Avdeev 2 , Doina Bica 1 , Oana Marinica 3 , Maria
Balasoiu 4 , Victor L. Aksenov 2 , Vasyl M. Garamus 5 , Andreas Schreyer 5
1 Laboratory of Magnetic Fluids, CFATR, Romanian Academy, Timisoara Division,
Timisoara, Romania – 2 Frank Laboratory of Neutron Physics, Joint Institute for Nuclear
Research, Dubna Moscow Reg., Russia – 3 National Center for Engineering of
Systems with Complex Fluids, Univ. Politehnica, Timisoara, Romania – 4 National
Institute for Nuclear Physics and Engineering, Bucharest, Romania – 5 GKSS Research
Centre, Geesthacht, Germany
A principle possibility to use biocompatible a short chain length monocarboxylic acid,
myristic acid (MA), is considered [1]. As a first step, this surfactant is used to coat
magnetite nanoparticles in non-polar organic liquids by the well-proven technology
[2,3]. It results in highly stable magnetic fluids. The new fluids are compared with
classical organic fluids stabilized by unsaturated oleic acid (OA). Parameters of the
log-normal size distribution of magnetite particles are obtained by small-angle scattering
of polarized neutrons (SANSPOL). The method reveals a great difference in the
particle size distribution function for the studied magnetic fluids, particularly a decrease
in the characteristic radius (from 4 to 2.5 nm) and polydispersity (from 0.38 to
0.28) when MA is used instead of OA. These finding is in agreement also with magnetization
and magneto-rheological analysis. One can conclude that monocarboxilic acids
show different efficiency in dispersing different size-fractions of nanometric magnetite
particles. While OA is proved to be highly efficient surfactant to stabilize nanomagnetite
over the wide size interval of 2-20 nm, shorter acids (like MA) stabilize partially
this interval dispersing in the carrier only a fraction of smaller particles. The size regulation
effect is reported when MA/OA mixtures are used in stabilization procedure [4].
This research project has been supported by the European Commission under the 6th
Framework Program through the Key Action: Strengthening the European Research
Area, Research Infrastructures. Contract nr: RII3-CT-2003-505925, GKSS, Germany,
as well as by the AEROSPATIAL research program of the Romanian Ministry of Education
and Research, contract OALM nr.111/2004. M.V.Avdeev acknowledges the
support from the INTAS Fellowship Grant for Young Scientists, Ref. N. 04-83-2582.
[1] M.V.Avdeev, D.Bica, L.Vékás, O.Marinica, M.Balasoiu, V.L.Aksenov, L.Rosta,
V.M.Garamus, A.Schreyer, Submitted to J. Mag. Mag. Mater. (2006).
[2] D.Bica, Rom. Rep. Phys. 47 (1995) 265-272.
[3] L.Vékás, et al., Progr. Colloid. Polym. Sci. 117 (2001) 104-109.
[4] D.Bica, M.V.Avdeev, O.Marinica, V.M.Garamus, L.Vekas, In EUROMECH Coll.
470, February 2006, Dresden, Germany.