INVERTED AND MULTIPLE NEMATIC EMULSIONS

We investigate experimentally the structures that form when small coll oidal particles are suspended in a nematic solvent. These structures a re anisotropic, and their formation is driven by interactions arising from the orientational elasticity of the nematic solvent. By using inv erted and multiple nematic emulsions composed of water droplets disper sed in a thermotropic liquid crystal, we identify the nature of these interactions, and demonstrate that they can be controlled by the ancho ring of the liquid crystal molecules at the surfaces of the droplets. When the anchoring is normal, the droplets form linear chains, suggest ing a long-range dipole-dipole attraction between the particles. By co ntrast, the interactions are repulsive at short range, and prevent con tact of the droplets, thereby stabilizing them against coalescence. Wh en the anchoring is planar, the droplets generate distortions that hav e a quadrupolar character. The resultant elastic interactions lead to more compact, but still anisotropic, clusters.