Regensburg 2010 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 33: Nonlinear Dynamics II

DY 33.5: Talk

Friday, March 26, 2010, 11:45–12:00, H46

Dynamics of Janus particles in a phase-separating binary mixture — •Vanessa Weith, Alexei Krekhov, and Walter Zimmermann — Theoretische Physik I, Universität Bayreuth, 95440 Bayreuth, Germany

Adding particles to a binary mixture induces an interesting dynamic coupling between the wetting of the particles and the phase separation of the mixture. Recently a new class of colloidal particles, so-called Janus particles, have been synthesized in large quantities [1]. Janus particles, named after the Roman god Janus, represent colloids with a different chemical composition of the surface of the two halves of a particle. Accordingly each half of a particle may be wetted preferentially by one component of the mixture.

We present the results of numerical simulations of the dynamics of Janus particles immersed in a phase-separating binary mixture based on a mean-field approach. When the two constituents of a binary mixture wet the two sides of a Janus particle differently, the particle induces a spatial variation of the concentration in their neighborhood. Accordingly, Janus particles in phase separating mixtures are trapped to interfaces, which leads to a complex dynamics.

Due to the strong localization of an interface, the diffusion of Janus particles is much more pronounced compared with isotropic particles. As a result of this fast diffusion the Janus particles placed initially at large distances may effectively approach each other and they can remain coupled in the case of an appropriate orientation.

[1] A. Walther and A. H. E. Müller, Soft Matter 4, 663-668 (2008)