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Title: Amphiphile-Induced Phase Transition of Liquid Crystals at Aqueous Interfaces

Abstract

We report that monolayer assemblies of amphiphiles at planar interfaces between thermotropic liquid crystals (LCs) and an aqueous phase can give rise to configurational transitions of the underlying LCs. A common assumption has been that a reconfiguration of the LC phase is caused by an interdigitation of the hydrophobic tails of amphiphiles with the molecules of the LC at the interface. A different mechanism is discovered here, whereby reorientation of the LC systems is shown to occur through lowering of the orientation-dependent surface energy of the LC due to formation of a thin isotropic layer at the aqueous interface. Using a combination of atomistic molecular dynamics simulations and experiments, we demonstrate that a monolayer of specific amphiphiles at an aqueous interface can cause a local nematic-to-isotropic phase transition of the LC by disturbing the antiparallel configuration of the LC molecules. Lastly, these results provide new insights into the interfacial, molecular-level organization of LCs that can be exploited for rational design of biological sensors and responsive systems.

Authors:
 [1];  [1];  [2]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [2]; ORCiD logo [4]
  1. Univ. of Chicago, IL (United States)
  2. Univ. of Wisconsin, Madison, WI (United States)
  3. Univ. of Massachusetts, Amherst, MA (United States)
  4. Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE; US Army Research Office (ARO)
OSTI Identifier:
1498497
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 10; Journal Issue: 43; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; aqueous phase; simulations and experiments; thermotropic liquid crystals; thin isotropic layer

Citation Formats

Ramezani-Dakhel, Hadi, Rahimi, Mohammad, Pendery, Joel, Kim, Young-Ki, Thayumanavan, Sankaran, Roux, Benoît, Abbott, Nicholas L., and de Pablo, Juan J. Amphiphile-Induced Phase Transition of Liquid Crystals at Aqueous Interfaces. United States: N. p., 2018. Web. doi:10.1021/acsami.8b09639.
Ramezani-Dakhel, Hadi, Rahimi, Mohammad, Pendery, Joel, Kim, Young-Ki, Thayumanavan, Sankaran, Roux, Benoît, Abbott, Nicholas L., & de Pablo, Juan J. Amphiphile-Induced Phase Transition of Liquid Crystals at Aqueous Interfaces. United States. doi:10.1021/acsami.8b09639.
Ramezani-Dakhel, Hadi, Rahimi, Mohammad, Pendery, Joel, Kim, Young-Ki, Thayumanavan, Sankaran, Roux, Benoît, Abbott, Nicholas L., and de Pablo, Juan J. Thu . "Amphiphile-Induced Phase Transition of Liquid Crystals at Aqueous Interfaces". United States. doi:10.1021/acsami.8b09639. https://www.osti.gov/servlets/purl/1498497.
@article{osti_1498497,
title = {Amphiphile-Induced Phase Transition of Liquid Crystals at Aqueous Interfaces},
author = {Ramezani-Dakhel, Hadi and Rahimi, Mohammad and Pendery, Joel and Kim, Young-Ki and Thayumanavan, Sankaran and Roux, Benoît and Abbott, Nicholas L. and de Pablo, Juan J.},
abstractNote = {We report that monolayer assemblies of amphiphiles at planar interfaces between thermotropic liquid crystals (LCs) and an aqueous phase can give rise to configurational transitions of the underlying LCs. A common assumption has been that a reconfiguration of the LC phase is caused by an interdigitation of the hydrophobic tails of amphiphiles with the molecules of the LC at the interface. A different mechanism is discovered here, whereby reorientation of the LC systems is shown to occur through lowering of the orientation-dependent surface energy of the LC due to formation of a thin isotropic layer at the aqueous interface. Using a combination of atomistic molecular dynamics simulations and experiments, we demonstrate that a monolayer of specific amphiphiles at an aqueous interface can cause a local nematic-to-isotropic phase transition of the LC by disturbing the antiparallel configuration of the LC molecules. Lastly, these results provide new insights into the interfacial, molecular-level organization of LCs that can be exploited for rational design of biological sensors and responsive systems.},
doi = {10.1021/acsami.8b09639},
journal = {ACS Applied Materials and Interfaces},
number = 43,
volume = 10,
place = {United States},
year = {2018},
month = {10}
}

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Cited by: 4 works
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Figures / Tables:

Fig. 1 Fig. 1: Dynamic optical response of a 5CB thin film to the self-assembly of amphiphiles at aqueous interfaces, and molecular dynamics simulations. (A, B) Optical images of a LC thin film, and schematic representations of the molecular orientation within the LC phase, before addition of an amphiphile (A), and aftermore » addition of a 150 µM solution of the amphiphile AMP2 (B). The LC film assumes a hybrid configuration before addition of AMP2, and transforms to a uniform configuration upon formation of an amphiphile monolayer. (C, D) Setup for molecular dynamics simulations (C), and a top-view snapshot of the AMP2-monolayer at the LC-water interface (D). A thin film of 5CB is primarily confined between vacuum and pure water. The monolayer-assembly of AMP2 is created by adding 1 mol/nm2 of the amphiphiles to the LC-water interface. The snapshot shows the color-coded profile of the second Legendre polynomial P2(𝑧) = 〈$\frac{3}{2}$ cos2 𝜃 −$\frac{1}{2}$〉. (E) Molecular structure of a 5CB molecule and the amphiphile molecule AMP2.« less

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Works referencing / citing this record:

Soft matter from liquid crystals
journal, January 2019

  • Kim, Young-Ki; Noh, JungHyun; Nayani, Karthik
  • Soft Matter, Vol. 15, Issue 35
  • DOI: 10.1039/c9sm01424a

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