Nematic colloids
By: Zahra Eskandari
From: CFTC - UL
At: Instituto de Investigação Interdisciplinar, Anfiteatro
[2012-04-24]
Nematic colloids are dispersions of colloidal particles in a nematic liquid crystal. In contrast with colloidal particles in simple fluids, where the interactions are dominated by van der Waals and entropic forces, nematic colloids interact through the nematic elastic deformations that induce long-range anisotropic forces. These forces are thousands of times stronger than in simple fluids and are responsible for the self-assembly of colloidal particles into a great variety of complex structures.
Recently, there has been some effort to assemble nematic colloids into periodic lattices in a attempt to manufacture colloidal structures that, combined with the mechanical and optical properties of nematics, could be used as photonic crystals. The main goal of a three-dimensional nematic colloidal crystal is yet to be achieved. However, a great variety of two-dimensional lattices have already been obtained experimentally. These structures are very sensible to the boundary conditions (anchoring) on the surface of the colloidal particles, which in turn determine their interaction at long and short distances.
In this talk, I will show how the anchoring conditions influence the particle pair interaction and how it affects the formation and symmetries of two-dimensional colloidal lattices.