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Title: Reconfigurable Multicompartment Emulsion Drops Formed by Nematic Liquid Crystals and Immiscible Perfluorocarbon Oils

Abstract

Liquid crystalline (LC) oils provide the basis of stimuli-responsive LC-in-water emulsions. Although past studies have explored the properties of single-phase LC emulsions, few studies have focused on complex multicompartment emulsions containing co-existing isotropic and LC domains. In this paper, we report a study of multiphase emulsions using LCs and immiscible perfluoroalkanes dispersed in water or glycerol (the latter continuous phase is used to enable characterization). We found that the nematogen 4'-pentyl-4-biphenylcarbonitrile (5CB) anchors homeotropically (perpendicularly) and weakly at liquid perfluorononane (F9) interfaces, consistent with the smectic layering of 5CB molecules. The proposed role of smectic layering is supported by experiments performed with 4-(trans-4-pentylcyclohexyl)benzonitrile, a nematogen that possesses a cyclohexyl group that frustrates the smectic packing and leads to tilted orientations at the F9 interface. By employing perfluorocarbon and hydrocarbon surfactants in combination with multiphase 5CB and F9 emulsion droplets dispersed in a continuous water or glycerol phase, we observe a range of emulsion droplet morphologies to form, including core–shell and Janus structures, with internal organizations that reflect an interplay of interfacial (anchoring energies; F9 and glycerol) and elastic energies within the confines of the geometry of the emulsion droplet. By comparing experimental observations to simulations of the LC–perfluorocarbon droplets basedmore » on a Landau-de Gennes model of the free energy, we place bounds on the orientation-dependent interfacial energies that underlie the internal ordering of these complex emulsions. Additionally, by forming core–shells emulsion droplets from 5CB (shell) and perfluoroheptane (cores), we demonstrate how a liquid-to-vapor phase transition in the perfluorocarbon core can be used to actuate the droplet and rapidly thin the nematic shell. Overall, the findingss reported in this paper demonstrate that multiphase LC emulsions formed from mixtures of perfluoroalkanes and LCs provide new opportunities to engineer hierarchical and stimuli-responsive emulsion systems.« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [3];  [2];  [1];  [4]; ORCiD logo [5]; ORCiD logo [1]
  1. Cornell Univ., Ithaca, NY (United States)
  2. Univ. of Chicago, IL (United States)
  3. Cornell Univ., Ithaca, NY (United States); Pohang Univ. of Science and Technology (Korea)
  4. Univ. of Wisconsin, Madison, WI (United States)
  5. Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States); Univ. of Chicago, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1616865
Grant/Contract Number:  
SC0004025
Resource Type:
Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 35; Journal Issue: 49; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Wang, Xin, Zhou, Ye, Palacio-Betancur, Viviana, Kim, Young-Ki, Delalande, Lily, Tsuei, Michael, Yang, Yu, de Pablo, Juan J., and Abbott, Nicholas L. Reconfigurable Multicompartment Emulsion Drops Formed by Nematic Liquid Crystals and Immiscible Perfluorocarbon Oils. United States: N. p., 2019. Web. doi:10.1021/acs.langmuir.9b02864.
Wang, Xin, Zhou, Ye, Palacio-Betancur, Viviana, Kim, Young-Ki, Delalande, Lily, Tsuei, Michael, Yang, Yu, de Pablo, Juan J., & Abbott, Nicholas L. Reconfigurable Multicompartment Emulsion Drops Formed by Nematic Liquid Crystals and Immiscible Perfluorocarbon Oils. United States. https://doi.org/10.1021/acs.langmuir.9b02864
Wang, Xin, Zhou, Ye, Palacio-Betancur, Viviana, Kim, Young-Ki, Delalande, Lily, Tsuei, Michael, Yang, Yu, de Pablo, Juan J., and Abbott, Nicholas L. Fri . "Reconfigurable Multicompartment Emulsion Drops Formed by Nematic Liquid Crystals and Immiscible Perfluorocarbon Oils". United States. https://doi.org/10.1021/acs.langmuir.9b02864. https://www.osti.gov/servlets/purl/1616865.
@article{osti_1616865,
title = {Reconfigurable Multicompartment Emulsion Drops Formed by Nematic Liquid Crystals and Immiscible Perfluorocarbon Oils},
author = {Wang, Xin and Zhou, Ye and Palacio-Betancur, Viviana and Kim, Young-Ki and Delalande, Lily and Tsuei, Michael and Yang, Yu and de Pablo, Juan J. and Abbott, Nicholas L.},
abstractNote = {Liquid crystalline (LC) oils provide the basis of stimuli-responsive LC-in-water emulsions. Although past studies have explored the properties of single-phase LC emulsions, few studies have focused on complex multicompartment emulsions containing co-existing isotropic and LC domains. In this paper, we report a study of multiphase emulsions using LCs and immiscible perfluoroalkanes dispersed in water or glycerol (the latter continuous phase is used to enable characterization). We found that the nematogen 4'-pentyl-4-biphenylcarbonitrile (5CB) anchors homeotropically (perpendicularly) and weakly at liquid perfluorononane (F9) interfaces, consistent with the smectic layering of 5CB molecules. The proposed role of smectic layering is supported by experiments performed with 4-(trans-4-pentylcyclohexyl)benzonitrile, a nematogen that possesses a cyclohexyl group that frustrates the smectic packing and leads to tilted orientations at the F9 interface. By employing perfluorocarbon and hydrocarbon surfactants in combination with multiphase 5CB and F9 emulsion droplets dispersed in a continuous water or glycerol phase, we observe a range of emulsion droplet morphologies to form, including core–shell and Janus structures, with internal organizations that reflect an interplay of interfacial (anchoring energies; F9 and glycerol) and elastic energies within the confines of the geometry of the emulsion droplet. By comparing experimental observations to simulations of the LC–perfluorocarbon droplets based on a Landau-de Gennes model of the free energy, we place bounds on the orientation-dependent interfacial energies that underlie the internal ordering of these complex emulsions. Additionally, by forming core–shells emulsion droplets from 5CB (shell) and perfluoroheptane (cores), we demonstrate how a liquid-to-vapor phase transition in the perfluorocarbon core can be used to actuate the droplet and rapidly thin the nematic shell. Overall, the findingss reported in this paper demonstrate that multiphase LC emulsions formed from mixtures of perfluoroalkanes and LCs provide new opportunities to engineer hierarchical and stimuli-responsive emulsion systems.},
doi = {10.1021/acs.langmuir.9b02864},
journal = {Langmuir},
number = 49,
volume = 35,
place = {United States},
year = {2019},
month = {10}
}

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Figures / Tables:

Figure 1 Figure 1: Molecular structures of the nematogens (A) 4′-pentyl-4-biphenylcarbonitrile (5CB), (B) 4-(trans-4-pentylcyclohexyl) benzonitrile (PCH5); (C) perfluorononane (F9) and (D) perfluoroheptane (F7).

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.