Specific salt effects on thermophoresis of charged colloids

Kyriakos A. Eslahian (1, 2) , Arghya Majee (3, 4, 5) , Michael Maskos (1) , Alois Würger (3)

1 ICT-IMM - Fraunhofer ICT-IMM
2 BAM Bundesanstalt für Materialforschung u. -prüfung
3 LOMA - Laboratoire Ondes et Matière d'Aquitaine
4 Max Planck Institute for Intelligent Systems [Tübingen]
5 Institut für Theoretische Physik [Braunschweig]

We study the Soret effect of charged polystyrene particles as a function of temperature and electrolyte composition. As a main result we find that the Soret coefficient is determined by charge effects, and that non-ionic contributions are small. In view of the well-known electric-double layer interactions, our thermal field-flow fractionation data lead us to the conclusion that the Soret effect originates to a large extent from diffusiophoresis in the salt gradient and from the electrolyte Seebeck effect, both of which show strong specific-ion effects. Moreover, we find that thermophoresis of polystyrene beads is fundamentally different from proteins and aqueous polymer solutions, which show a strong non-ionic contribution.

Domaines: Matière Molle [cond-mat.soft]

Kyriakos A. Eslahian, Arghya Majee, Michael Maskos, Alois Würger. Specific salt effects on thermophoresis of charged colloids. Soft Matter, 2014, 10, pp.1931-1936. ⟨10.1039/C3SM52779D⟩. ⟨hal-00952801⟩