Colloid Dynamics at Anisotropically Curved Interfaces

Spheres love to pack as hexagons. You can see this in any grocery shop where they sell oranges. This hexagonal packing is most efficient with regards to space. If colloids (at an interface) experience a net attractive interaction, they do the same. However, this is no longer the case if either the colloids have an anisotropic shape, or the interface has an anisotropic curvature. Ershov et al.[1] found that in this case, particles pack in square conformations.

In this project we continue with a systematic investigation of the behaviour of spherical colloids on cylindrically curved oil-water interfaces. Particle positions are determined with standard tracking algorithms. Then we identify free particles and particles that form pairs/clusters. The random motion of free particles in this system is used to obtain information about the friction coefficient. The motion of pairs of particles in equilibrium is used to determine the interaction energy at short separation, and the approach curve of two particles before they reach equilibrium is used to find information about the shape of the energy curve at positions far from the equilibrium distance.

References

[1] Ershov et al. Capillarity-induced ordering of spherical colloids on an interface with anisotropic curvature. PNAS. 110 (2013)23. - ISSN 0027-8424 - p. 9220 - 9224.