Berlin 2015 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 40: Charged Soft Matter II
CPP 40.5: Talk
Wednesday, March 18, 2015, 10:30–10:45, PC 203
Specific salt effects on thermophoresis of charged colloids — •Arghya Majee1, Kyriakos A. Eslahian2, Michael Maskos2, and Alois Würger3 — 1Max Planck Institute IS & University of Stuttgart, Germany — 2Fraunhofer ICT-IMM, Mainz, Germany — 3LOMA, Université de Bordeaux & CNRS, France
The electrolyte Seebeck effect determines to a large extent the properties of charged colloids that are heated or subject to a thermal gradient. The electric double layer responds to a non uniform temperature through several mechanims, resulting in a significant thermocharge and transport to the hot or to the cold side [1]. In this contribution we discuss the Soret effect of charged polystyrene particles as a function of temperature and electrolyte composition [2]. 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.
References:
[1] A. Majee, A. Würger, Phys. Rev. Lett. 108, 118301 (2012).
[2] Kyriakos A. Eslahian, A. Majee, M. Maskos, and A. Würger, Soft Matter 10, 1931 (2014).