title: Nematic-field-driven positioning of particles in liquid crystal droplets.
abstract: Common nematic oils, such as 5CB, experience planar anchoring at aqueous interfaces. When these oils are emulsified, this anchoring preference and the resulting topological constraints lead to the formation of droplets that exhibit one or two point defects within the nematic phase. Here, we explore the interactions of adsorbed particles at the aqueous interface through a combination of experiments and coarse-grained modeling, and demonstrate that surface-active particles, driven by elastic forces in the droplet, readily localize to these defect regions in a programmable manner. When droplets include two nanoparticles, these preferentially segregate to the two poles, thereby forming highly regular dipolar structures that could serve for hierarchical assembly of functional structures. Addition of sufficient concentrations of surfactant changes the interior morphology of the droplet, but pins defects to the interface, resulting in aggregation of the two particles.
authors: Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691, USA and Argonne National Laboratory, Argonne, Illinois 60349, USA.
authors: Jonathan K
authors: JK
authors: Whitmer
authors: Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691, USA.
authors: Xiaoguang
authors: X
authors: Wang
authors: Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691, USA.
authors: Frederic
authors: F
authors: Mondiot
authors: Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691, USA.
authors: Daniel S
authors: DS
authors: Miller
authors: Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691, USA.
authors: Nicholas L
authors: NL
authors: Abbott
authors: Argonne National Laboratory, Argonne, Illinois 60349, USA and Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA.
authors: Juan J
authors: JJ
authors: de Pablo