Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 45: Colloids and Complex Liquids II

CPP 45.9: Talk

Thursday, March 14, 2013, 17:30–17:45, H40

Percolation thresholds and critical exponents of colloidal suspensions in bulk and confinement — •Helge Neitsch and Sabine H. L. Klapp — Institut für Theoretische Physik, TU Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany

We performed extensive grand canonical Monte Carlo simulations to investigate the percolation transition of spherical colloids a) in the bulk phase and b) confined between two parallel, chemical undecorated walls (slit pore) [1]. The interaction between the colloids is modeled through a square-well potential with an attraction range of only 4% of the hard core diameter to mimic the ultra-short ranged nature of depletion attractions [2]. Applying a finite-size analysis, we investigated the density threshold of the connectedness percolation at several wall separations (width of the slit pore). Increasing the wall separation, we found a shift of the percolation threshold towards the bulk value obtained from an unconfined, in other respects identical system. We could explain this shift by scaling arguments, which are usually applied in the framework of cross-over scaling of the vapor-liquid critical point of simple liquids in slit pores [3]. In addition we studied the critical exponents of the percolation transition and found them to be remarkably insensitive to the width of the slit pore.
[1] H. Neitsch and S. H. L. Klapp, submitted, arXiv:1211.1027 (2012)

[2] P. J. Lu, E. Zaccarelli, F. Ciulla, A. B. Schofield, F. Sciortino, and D. A. Weitz, Nature 453, 499 (2008)

[3] R. L. C. Vink, K. Binder, and J. Horbach, Phys. Rev. E 73, 056118 (2006)