Dresden 2014 – scientific programme

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BP: Fachverband Biologische Physik

BP 18: Complex Fluids and Soft Matter (joint DY/CPP/BP)

BP 18.3: Talk

Tuesday, April 1, 2014, 10:00–10:15, ZEU 118

Friction of Colloidal Crystals on Commensurate and Incommensurate Substrates — •Aleksandar Mijailović and Michael Schmiedeberg — Theoretische Physik 2, Heinrich-Heine Universität, Düsseldorf, Germany

Among the fascinating properties of quasicrystals - structures that possess long range order but no translational symmetry - is the very low friction that was observed when a periodic crystal is moved over the surface of a quasicrystal [1]. Here we want to explore whether there are geometrical reasons for the small friction.

Using Brownian Dynamics simulations, the friction properties of 3D colloidal fcc-crystals on substrates with different geometries are studied. We measure the friction as a function of the drag force applied on the crystal, from which the friction coefficient is extracted. We repeat this analysis for commensurate, incommensurate perodic, and quasicrystalline substrates and investigate the effect of incommensurability as well as aperiodicity.

The (charged) colloidal particles are interacting via the Asakura-Oosawa Model, i.e., a superposition of the screened-Coulomb potential and an attractive term, which is due to the presence of non-adsorbing polymers (not treated explicitly). Finally, our results are compared to the 2D case (cf., e.g., [2].

1. J. Y. Park et al., Science 309, 1354 (2005).
2. T. Bohlein et al., Nat. Mat. 11, 126 (2012).