Characterization of adsorbate-induced ordering transitions of liquid crystals within monodisperse droplets.

The ordering of liquid crystals (LCs) within micrometer-sized droplets is known to depend strongly on the presence of interfacial adsorbates, although the exact sequence of ordered equilibrium states that accompany a change in interfacial anchoring from tangential to perpendicular has not been established. In this paper, we report use of a methodology that permits the preparation of monodisperse LC droplets in aqueous phases to investigate ordering transitions in the LC droplets that accompany the adsorption of amphiphiles at the aqueous−LC droplet interface. By using an amphiphile that undergoes reversible adsorption at the aqueous−LC interface (sodium dodecylsulfate, SDS), we identified six distinct topologically ordered states of the LC droplets as a function of increasing concentration of SDS. We exploited the reversible adsorption of the SDS to LC droplets with diameters of 8.0 ± 0.2 μm to confirm that these topological states are equilibrium ones. We also exposed LC droplets to a continuous gradient...