| 1. |
- Atri, Ria S., et al.
(author)
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Morphology Modulation of Ionic Surfactant Micelles in Ternary Deep Eutectic Solvents
- 2020
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In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 124:28, s. 6004-6014
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Journal article (peer-reviewed)abstract
- Deep eutectic solvents (DES) are potentially greener solvents obtained through the complexation of simple precursors which, among other applications, have been investigated in recent years for their ability to support the self-assembly of amphiphilic molecules. It is crucial to understand the factors which influence surfactant solubility and self-assembly with respect to the interaction of the surfactant molecule with the DES components. In this work, small-angle neutron scattering (SANS) has been used to investigate the micellization of cationic (CnTAB) and anionic (SDS) surfactants in a ternary DES comprising choline chloride, urea, and glycerol, where the hydrogen bond donors are mixed in varying molar ratios. The results show that in each case either globular or rodlike micelles are formed with the degree of elongation being directly dependent on the composition of the DES. It is hypothesized that this composition dependence arises largely from the poor solubility of the counterions in the DES, especially at low glycerol content, leading to a tighter binding of the counterion to the micelle surface and giving rise to micelles with a high aspect ratio. This potential for accurate control over micelle morphology presents unique opportunities for rheology control or to develop templated syntheses of porous materials in DES, utilizing the solvent composition to tailor micelle shape and size, and hence the pore structure of the resulting material.
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| 2. |
- Bathke, Elly K., et al.
(author)
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The influence of chirality on the structure of a tartaric acid-choline chloride deep eutectic solvent
- 2024
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In: Journal of Molecular Liquids. - 0167-7322. ; 402
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Journal article (peer-reviewed)abstract
- The wide range of properties, relative ease and low cost of using Deep Eutectic Solvents garners them interest in an ever expanding range of applications. Among common DES components many are naturally occurring chiral molecules. Here we present the liquid structure of either single enantiomeric or racemic tartaric acid with choline chloride at a molar ratio of 2 choline chloride to 1 tartaric acid, as well as the influence of low amounts of added water (2:1:2) from neutron scattering data with H/D isotropic substitution, refined using empirical potential structure refinement. We show that the overall structure remains the same between the different enatiomeric compositions, with small differences in interactions only occurring between the tartaric acid molecules. The overall structure is also robust towards hydration, similar to what has been found in other DES. We also compare our structures to the structures of DES comprising of similar carboxylic acids (1:1 choline chloride - malic acid, 1:1 choline chloride - oxalic acid), finding overall similar dominant interactions, with differences that may be attributable to the number of available hydrogen bonding sites and steric effects.
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| 3. |
- Manasi, Iva, et al.
(author)
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Cationic Micelles in Deep Eutectic Solvents: Effects of Solvent Composition
- 2024
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In: Faraday Discussions. - 1359-6640.
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Journal article (peer-reviewed)abstract
- Deep eutectic solvents (DES) are mixtures of hydrogen bond donors and acceptors that form strongly hydrogen-bonded room temperature liquids. Changing the H-bonding components and their ratios can alter the physicochemical properties of deep eutectic solvents (DES). Recent studies have shown p-toluene sulfonic acid (pTSA) forms room temperature liquids with choline chloride (ChCl) at different molar ratios: 1:1, 1:2 and 2:1 [Rodriguez Rodriguez et al., ACS Sustainable Chemistry and Engineering, 2019, 7(4), 3940]. They also showed that the composition affects the physical properties of these liquids and their ability to dissolve metal oxides. In this work we evaluate the solubility and self-assembly of cationic surfactants alkyltrimethyl ammonium bromides (CnTAB) in these pTSA/ChCl based liquids. CnTABs are insoluble in 1pTSA:2ChCl, whereas in 1pTSA:1ChCl and 2pTSA;1ChCl they form micelles. We characterise CnTAB (n=12, 14, 16) micelles using Small Angle Neutron Scattering and also look at interaction of water with the micelles. These studies help determine the interaction of DES components with the surfactant and the influence of varying pTSA and water ratios on these interactions. This provides potential for controlled surfactant templating and for tuning rheology modification in such systems.
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| 4. |
- Manasi, Iva, et al.
(author)
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Nanostructure in Amphiphile-Based Deep Eutectic Solvents
- 2023
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In: Langmuir. - 0743-7463. ; 39:47, s. 16776-16784
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Journal article (peer-reviewed)abstract
- Deep eutectic solvents (DESs) are an emerging class of modern, often “green” solvents with unique properties. Recently, a deep eutectic system based on amphiphilic surfactant N-alkyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (C12 & C14 sulfobetaine) and (1S)-(+)-10-camphor-sulfonic acid in the molar ratio 1:1.5 has been reported. Nanostructuring can be expected in this DES due to the nature of the components. In this work, we have investigated the native nanostructure in the DES comprising C12-C18 alkyl chain sulfobetaines with camphor sulfonic acid and how it interacts with polar and nonpolar species, water and dodecane, respectively, using small angle neutron scattering. By using contrast variation to highlight the relative position of the solvent components and additives, we can resolve the structure of the solvent and how it changes upon interaction with water and dodecane. Scattering from the neat DES shows structures corresponding to the self-assembly of sulfobetaines; the size of the structure increases as the alkyl chain length of the sulfobetaines increases. Water and dodecane interact, respectively, with the hydrophilic and hydrophobic moieties in the DES structure, primarily the sulfobetaine, thereby swelling and solvating the entire structure. The extent of the shift of the peak position, and the swelling, depend on concentration of the additive. The solution phase organization and the interaction of polar and nonpolar species as observed here, have the potential to affect the ordering of inorganic or polymeric materials grown in such solvents, paving new avenues for templating applications.
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