Berlin 2012 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 32: Soft Matter II
DY 32.2: Vortrag
Freitag, 30. März 2012, 10:15–10:30, MA 144
Colloid crystallization on strained substrates — •Stefan Frieder Hopp1, Andreas Heuer1, John Savage2, and Itai Cohen3 — 1Institut für Physikalische Chemie, Universität Münster, 48149 Münster, Germany — 2Liquidia Technologies, Research Triangle Park, North Carolina 27709, USA — 3Department of Physics, Cornell University, Ithaca, New York 14853, USA
The crystallization behavior of charge-stabilized polystyrene colloids on a colloidal monolayer [1] is modeled by kinetic Monte Carlo simulations. In this context, the local properties of particles in simply shaped colloid clusters are studied as a function of substrate strain due to lattice mismatch. The colloidal depletion interaction is described by a short-range Morse potential. It is shown the experimental data for isotropically strained square lattices can be reproduced. Putting the focus on a particular intermediate strain, the behavior of the colloid crystals is examined with regard to the dependence on temperature. Remarkably, one observes the crystals melt with decreasing temperature, contrary to general expectation. Based on a particle dimer, this is explained by the interplay of energy and entropy both of which show a distinct dependence on the height of the particles as well as the particle-particle distance.
[1] R. Ganapathy, M. R. Buckley, S. J. Gerbode, I. Cohen, Science, 327, 445 (2010).