Europhys. Lett.
Volume 72, Number 4, November 2005
Page(s) 671 - 677
Section Interdisciplinary physics and related areas of science and technology
Published online 14 October 2005
Europhys. Lett., 72 (4), pp. 671-677 (2005)
DOI: 10.1209/epl/i2005-10279-7

Shape-induced capillary interactions of colloidal particles

E. A. van Nierop1, 2, M. A. Stijnman2 and S. Hilgenfeldt3, 4, 2

1  Division of Engineering and Applied Sciences, Harvard University Cambridge, MA 02138, USA
2  University of Twente, Faculty of Applied Physics, Physics of Fluids P.O. Box 217, 7500 AE Enschede, the Netherlands
3  Department of Engineering Sciences and Applied Mathematics Northwestern University - Evanston, IL 60208, USA
4  Department of Mechanical Engineering, Northwestern University Evanston, IL 60208, USA

received 27 July 2005; accepted 21 September 2005
published online 14 October 2005

We show that near-spherical micrometer-sized colloidal particles at an interface of two fluids experience inter-particle forces merely as a consequence of their shape-induced capillary interaction. The interaction is strong even if the deviations from sphericity are on the nm-scale, and can hardly be avoided in experiment. For particles of 2$\un\mu$m radius, a deformation of $20\un{nm}$ can result in an attractive potential of 2kBT at a distance of 4 particle radii. Dynamical simulations of many particles confirm that the forces lead to aggregates of dendritic or hexagonal-lattice type. The latter pattern exhibits strong herringbone-phase orientational order.

82.70.Dd - Colloids.
68.03.Cd - Surface tension and related phenomena.

© EDP Sciences 2005