Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 9: POSTER: Colloids and Nanoparticles
CPP 9.14: Poster
Monday, March 26, 2007, 16:00–18:00, Poster B
Capillary interaction between ellipsoidal colloids at a fluid interface — •Hartwig Lehle1,2 and Martin Oettel1,3 — 1Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart — 2Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart — 3Institut für Physik, WA 331, Johannes-Gutenberg-Universität Mainz, 55099 Mainz
In two recent publications, Loudet et al. describe the behavior of µm-sized ellipsoidal colloids trapped at a water-oil interface [1,2]. They find a strong anisotropic attractive force between the colloids which leads the formation of complex chain- or raftlike structures at the interface and which can be qualitatively explained by the capillary interaction due to a quadrupolar meniscus deformation caused by the particle’s anisotropy. A thorough theoretical investigation of these phenomena is, however, missing so far.
In a systematic approach we derive a quadratic free energy functional of the interface and the colloids trapped at it. Upon minimizing the free energy we calculate the equilibrium meniscus profiles of both, a single ellipsoid and two ellipsoids in arbitrary orientation with respect to each other. Finally, from the interface profiles we determine the orientation dependent capillary force between the ellipsoidal particles and discuss the results in detail.
[1] J. C. Loudet, A. M. Alsayed, J. Zhang, and A. G. Yodh, Phys. Rev. Lett. 94, 018301 (2005)
[2] J. C. Loudet, A. G. Yodh, and B. Pouligny, Phys. Rev. Lett. 97, 018304 (2006)