Soret motion in non-ionic binary molecular mixtures

Yves Leroyer (1) , Alois Würger (1)

1 LOMA - Laboratoire Ondes et Matière d'Aquitaine

We study the Soret coefficient of binary molecular mixtures with dispersion forces. Relying on standard transport theory for liquids, we derive explicit expressions for the thermophoretic mobility and the Soret coefficient. Their sign depends on composition, the size ratio of the two species, and the ratio of Hamaker constants. Our results account for several features observed in experiment, such as a linear varition with the composition; they confirm the general rule that small molecules migrate to the warm, and large ones to the cold.

Mots clés: thermal diffusion; Soret effect; molecular mixtures; polymer thermophoresis

Domaines: Matière Molle [cond-mat.soft]

Yves Leroyer, Alois Würger. Soret motion in non-ionic binary molecular mixtures. Journal of Chemical Physics, 2011, 135 (5), pp.054102. ⟨10.1063/1.3615954⟩. ⟨hal-00617280⟩