Manipulation of Colloids by a Nonequilibrium Depletion Force in a Temperature Gradient

Hong-Ren Jiang, Hirofumi Wada, Natsuhiko Yoshinaga, and Masaki Sano
Phys. Rev. Lett. 102, 208301 – Published 20 May 2009
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Abstract

The nonequilibrium distribution of colloids in a polymer solution under a temperature gradient is studied experimentally. A slight increase of local temperature by a focused laser drives the colloids towards the hot region, resulting in the trapping of the colloids irrespective of their own thermophoretic properties. An amplification of the trapped colloid density with the polymer concentration is measured, and is quantitatively explained by hydrodynamic theory. The origin of the attraction is a migration of colloids driven by a nonuniform polymer distribution sustained by the polymer’s thermophoresis. These results show how to control the thermophoretic properties of colloids.

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  • Received 23 February 2009

DOI:https://doi.org/10.1103/PhysRevLett.102.208301

©2009 American Physical Society

Authors & Affiliations

Hong-Ren Jiang1, Hirofumi Wada2, Natsuhiko Yoshinaga1, and Masaki Sano1

  • 1Department of Physics, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan
  • 2Yukawa Insititute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan

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Issue

Vol. 102, Iss. 20 — 22 May 2009

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