Spherical nematic shells with a prolate ellipsoidal core

Journal Article · Thu Sep 21 00:00:00 EDT 2017 · Soft Matter

DOI:https://doi.org/10.1039/c7sm01403a· OSTI ID:1498502

Sadati, Monirosadat ^[1]; Zhou, Ye  ^[2]; Melchert, Drew ^[2]; Guo, Ashley ^[2]; Martinez-Gonzalez, Jose A.  ^[1]; Roberts, Tyler F. ^[2]; Zhang, Rui ^[2]; de Pablo, Juan J.  ^[1]

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1. Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
2. Univ. of Chicago, IL (United States)

We report that liquid crystal shells have attracted considerable attention in recent years. In such systems, a combination of confinement and curvature generates topological defect structures that do not exist in the bulk. Past studies, however, have largely focused on perfectly spherical shells, and little attention has been devoted to the impact of core geometry on the configuration and arrangement of topological defects. In this work, a microfluidic glass capillary device is used to encapsulate spherical and prolate ellipsoidal particles in nematic liquid crystal (LC) droplets dispersed in aqueous media. Our experimental studies show that, when trapped inside a radial LC droplet, spherical particles with both homeotropic and planar anchoring are highly localized at the droplet's center. While the radial configuration of the LC droplets is not altered by a homeotropic particle, polystyrene particles with strong planar anchoring disturb the radial ordering, leading to a twisted structure. Experiments indicate that off-center particle positions can also arise, in which defects are displaced towards the vicinity of the droplet's surface. In contrast, when prolate ellipsoidal particles are encapsulated in a thick radial LC shell, the minimum free energy corresponds to configurations where the particle is positioned at the droplet center. Lastly, in this case, defects arise at the two ends of the prolate ellipsoid, where the curvature of the particle is maximal, leading to the formation of peculiar hybrid and twisted structures.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; U.S. Army Research Laboratory - U.S. Army Research Office (ARO); National Science Foundation (NSF)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1498502
• Journal Information: Soft Matter, Vol. 13, Issue 41; ISSN 1744-683X
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY