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Evidence for an L3 phase in ternary deep eutectics : composition-induced L3-to-Lα transition of AOT

Hammond, Oliver S. ; Elstone, Naomi S. ; Doutch, James ; Li, Peixun and Edler, Karen J. LU orcid (2023) In Nanoscale 15(47). p.19314-19321
Abstract

Pure and hydrated deep eutectic solvents (DES) are proposed to form self-assembled nanostructures within the fluid bulk, similar to the bicontinuous L3 phase common for ionic liquids (ILs). Labelled choline chloride : urea : water DES were measured using small-angle neutron scattering (SANS), showing no long-range nanostructure. However, solutions of the surfactant AOT in this DES yielded scattering consistent with the L3 “sponge” phase, which was fitted using the Teubner-Strey model. A disclike model gave local structural information, namely, a linear increase in radius versus solvent water content (w = molar ratio of DES : water), eventually forming large, turbid lamellar phases at 10w; an... (More)

Pure and hydrated deep eutectic solvents (DES) are proposed to form self-assembled nanostructures within the fluid bulk, similar to the bicontinuous L3 phase common for ionic liquids (ILs). Labelled choline chloride : urea : water DES were measured using small-angle neutron scattering (SANS), showing no long-range nanostructure. However, solutions of the surfactant AOT in this DES yielded scattering consistent with the L3 “sponge” phase, which was fitted using the Teubner-Strey model. A disclike model gave local structural information, namely, a linear increase in radius versus solvent water content (w = molar ratio of DES : water), eventually forming large, turbid lamellar phases at 10w; an L3-to-Lα transition was observed. Simultaneous multi-contrast SANS fits show the surfactant headgroup region is dominated by interactions with poorly-soluble Na+ at low water contents, and numerically-superior [cholinium]+ as water content increases. The modified interfacial Gaussian curvature from cation : anion volume matching stabilizes the lamellar morphology, allowing the bilayer aggregation number to increase.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Nanoscale
volume
15
issue
47
pages
8 pages
publisher
Royal Society of Chemistry
external identifiers
  • pmid:37997686
  • scopus:85178647142
ISSN
2040-3364
DOI
10.1039/d3nr03689h
language
English
LU publication?
yes
id
8acab5c7-42a8-4081-831a-6b59f17de3b0
date added to LUP
2023-12-18 08:15:35
date last changed
2024-04-16 20:29:55
@article{8acab5c7-42a8-4081-831a-6b59f17de3b0,
  abstract     = {{<p>Pure and hydrated deep eutectic solvents (DES) are proposed to form self-assembled nanostructures within the fluid bulk, similar to the bicontinuous L<sub>3</sub> phase common for ionic liquids (ILs). Labelled choline chloride : urea : water DES were measured using small-angle neutron scattering (SANS), showing no long-range nanostructure. However, solutions of the surfactant AOT in this DES yielded scattering consistent with the L<sub>3</sub> “sponge” phase, which was fitted using the Teubner-Strey model. A disclike model gave local structural information, namely, a linear increase in radius versus solvent water content (w = molar ratio of DES : water), eventually forming large, turbid lamellar phases at 10w; an L<sub>3</sub>-to-L<sub>α</sub> transition was observed. Simultaneous multi-contrast SANS fits show the surfactant headgroup region is dominated by interactions with poorly-soluble Na<sup>+</sup> at low water contents, and numerically-superior [cholinium]<sup>+</sup> as water content increases. The modified interfacial Gaussian curvature from cation : anion volume matching stabilizes the lamellar morphology, allowing the bilayer aggregation number to increase.</p>}},
  author       = {{Hammond, Oliver S. and Elstone, Naomi S. and Doutch, James and Li, Peixun and Edler, Karen J.}},
  issn         = {{2040-3364}},
  language     = {{eng}},
  month        = {{11}},
  number       = {{47}},
  pages        = {{19314--19321}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Nanoscale}},
  title        = {{Evidence for an L<sub>3</sub> phase in ternary deep eutectics : composition-induced L<sub>3</sub>-to-L<sub>α</sub> transition of AOT}},
  url          = {{http://dx.doi.org/10.1039/d3nr03689h}},
  doi          = {{10.1039/d3nr03689h}},
  volume       = {{15}},
  year         = {{2023}},
}