STABILITY OF LIQUID-CRYSTALLINE MACROEMULSIONS

The topological stability of emulsions of liquid crystal in water (gly cerol) matrices is demonstrated for a wide range of materials and conc entrations. Coalescence is prevented by an energy barrier for a topolo gical ring defect formation in a neck between the two merging droplets . There is a characteristic size of emulsion droplets, typically tens of micrometres or more, controlled by the balance of elastic and ancho ring energies of the liquid crystal. On removal of liquid crystallinit y (by raising the temperature above T-m in thermotropic nematic materi als, for example) the energy barriers for coalescence disappear and em ulsion droplets can merge quickly, controlled only by the traditional kinetic effects. Practical applications of this effect, as well as som e wider theoretical implications are discussed in the end.