This presentation will describe the use of liquid crystal (LC)-in-water emulsions for the templated assembly of either spherical or non-spherical particles with organized, chemically-distinct domains located on the surfaces of the particles. The approach involves the positioning of solid colloids at the surfaces of the LC emulsion droplets, via interactions mediated by the elasticity of the LC and topological defects that form predictably at surfaces of water-dispersed LC droplets. Specifically, we have found that three key interactions underlie organized assemblies formed by colloids at the curved surfaces of water-dispersed nematic LC microdroplets: (i) a long-range attraction of the adsorbed colloids to regions of the droplet interface at which splay distortion of the LC is at a maximum (splay attraction), (ii) inter-colloid quadrupole—quadrupole elastic interactions (the result of a quadrupolar topological defect structure about the colloids), and (iii) electrostatic repulsion between colloids. These three interactions promote formation of hexagonal arrays of colloids at well-defined locations on the LC droplet interface. In contrast, for the case of colloids at a flat aqueous—LC interface, the splay attraction is absent and the electrostatic repulsion keeps colloids separated under conditions of low ionic strength in the aqueous phase. Thus, the influence of splay attraction on the curved LC droplet interface is two-fold. It both overcomes repulsive interactions to promote the ordering of colloids on the surfaces of LC droplets, and plays a key role in determining the morphology of the assembly formed. Overall, the results to be discussed in this presentation provide guidance for the design of chemically patchy particles (including Janus particles) by advancing our understanding of the directed assembly of colloids at interfaces of LC droplets.<br/>

Organized assemblies of colloids formed at the interfaces of micrometer-sized droplets of liquid crystal: Enabling the synthesis of patchy and nonspherical particles

249th National Meeting (2015)

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