Topological Changes in Bipolar Nematic Droplets under Flow

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Original Entry: Aaron Goldfain, AP 225, Fall 2012

UNDER CONSTRUCTION

General Information

Authors: A. Fernández-Nieves, D. R. Link, M. Márquez, and D. A. Weitz

Publication: A. Fernández-Nieves, D. R. Link, M. Márquez, and D. A. Weitz. Topological Changes in Bipolar Nematic Droplets under Flow. Phys. Rev. Lett. (2007) vol. 98 article 087801.

Keywords: liquid crystal, nematic, microfluidic devices, emulsion, droplet.

Summary

Example Figure

The Poincaré theorem asserts that drops of nematic liquid crystal must always have a topological surface charge of +2, but a variety of defect and director configurations satisfy this. This Letter describes a method to change the configuration of such drops. In short, the defects in nematic droplets that flow through a microfluidic device are shown to oscillate between two equilibrium configurations.

The director field within nematic liquid crystal drops is characterized by the boundary conditions on the surface of the drop. Typically, the molecules of the liquid crystal have normal or planar anchoring to the surface. Normal anchoring means the director field is perpendicular to the surface, and planar means it is parallel to the surface. The nematic drops considered in this Letter are subject to planar anchoring at the boundary, for which there are three main defect configurations, shown in Figure 1.

method/preparation

observations/interpretation

Discussion

Discussion here

Reference

[1] A. Fernández-Nieves, D. R. Link, M. Márquez, and D. A. Weitz. Topological Changes in Bipolar Nematic Droplets under Flow. Phys. Rev. Lett. (2007) vol. 98 article 087801.