E. Pairam, J. Vallamkondu, V. Koning, B. C. van Zuiden, M. A. Bates, V. Vitelli, A. Fernandez Nieves
We stabilize nematic droplets with handles against surface-tension-driven instabilities using a yield-stress material as the outer fluid and study the complex nematic textures and defect structures that result from the competition between topological constraints and the elasticity of the nematic liquid crystal. We uncover a surprisingly persistent twisted configuration of the nematic director inside the droplets, which we explain by calculating the elusive saddle-splay contribution to the elastic free energy. For toroidal surfaces, this saddle-splay energy tends to screen the twisting energy resulting in a spontaneous symmetry-breaking transition from the untwisted to the twisted state that persists irrespective of aspect ratio. For droplets with additional handles, we observe in experiments and computer simulations two additional -1 surface defects per handle located in regions with local saddle geometry, where elastic distortions are minimized.
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http://arxiv.org/abs/1212.1771
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