Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: Colloids and Complex Liquids II - Dynamics and Mechanical Properties
CPP 39.3: Vortrag
Donnerstag, 17. März 2011, 11:00–11:15, ZEU 222
Transient Soret-melting of binary glasses by hot colloids — •Florian Schwaiger and Werner Köhler — Physikalisches Institut, Universität Bayreuth, Germany
Metallic nanoparticles have been investigated for many years in manifold research fields due to their outstanding optical, electronic and thermal properties in soft condensed matter. We have heated gold colloids with a diameter of 250 nm by laser irradiation and used them as microscopic heat sources in a polystyrene/toluene solution. Due to the high absorbance at the plasmon resonance wavelength around 532 nm, significant temperature gradients ∇ T ∝ 1/r2 can be achieved in the close vicinity of the particles on length scales below the diffraction limit. As a consequence of the Soret effect, there is a strong nonlinear coupling to the order parameter, the local composition of the binary system. In this binary glass former, a bubble of high mobility due to local toluene enrichment, accompanied by a drastic lowering of the glass transition temperature Tg, is created around the laser-heated particle. Accordingly, the colloidal particle is trapped within a cage of low friction that dynamically forms around the colloid and follows its position with a certain retardation. Outside of this bubble the colloids are virtually immobile.