Speaker
Description
Modulating micelle morphology and electrostatic correlations through specific ion interactions in deep eutectic solvents
Adrian Sanchez-Fernandez, Andrew Jackson and Karen Edler
Food Technology, Engineering and Nutrition, Lund University, Lund, Sweden.
European Spallation Source, Lund, Sweden.
Department of Chemistry, University of Bath, Bath, United Kingdom.
adrian.sanchez-fernandez@food.lth.se
In recent years, many studies into green solvents have been performed and deep eutectic
solvents (DES) have emerged as environmentally friendly alternatives in many fields, such as
separation processes, metal processing, biocatalysis and electrodeposition.[1] DES are green
solvents obtained through the combination of cheap and simple organic compounds, where
the interaction between the precursors promotes a depression in the melting point that
allows the mixture to remain liquid at room temperature. Moreover, the combination of
different precursors provides a certain control over the physicochemical properties of the
solvent (e.g. solvent polarity and charge density). Thus, DES are regarded as task-specific
“cocktails”, where the properties of the solvent can be tuned to suit particular applications.
Recent developments have shown the ability of DES to support amphiphile self-assembly,
bringing the possibility to develop sustainable alternatives for surfactant templating, drug
delivery and biosensing, among others. Here we will explore the self-assembly of surfactants
in DES as probed using small-angle neutron scattering. The increase of charge density in the
solvent is shown to promote micelle growth through electrostatic screening in comparison to
more neutrally charged DES environments.[2,3] In addition, the combined effect of
hydrophobic and electrostatic interactions through the addition of hydrotropic salts leads to
a profound change in micelle shape, resulting in the formation of worm-like micelles.[4]
Finally, our latest results in the study of long-range colloidal interactions in DES will be
presented. Aiming to gain a better understanding of the fundamental aspects of amphiphile
self-assembly in these solvents, we will present details of the micellisation with varied
physicochemical properties of the solvent, salt addition and counterion substitution.
[1] B.B. Hansen et al., Deep Eutectic Solvents: A Review of Fundamentals and Applications, Chem. Rev.
121(3) (2021) 1232-1285.
[2] A. Sanchez-Fernandez et al., Surfactant-Solvent Interaction Effects on the Micellization of Cationic
Surfactants in a Carboxylic Acid-Based Deep Eutectic Solvent, Langmuir 33(50) (2017) 14304-14314.
[3] A. Sanchez-Fernandez et al., Micellization of alkyltrimethylammonium bromide surfactants in choline
chloride:glycerol deep eutectic solvent, Phys. Chem. Chem. Phys. 18(48) (2016) 33240-33249.
[4] A. Sanchez-Fernandez et al., Complex by design: Hydrotrope-induced micellar growth in deep eutectic
solvents, J. Colloid Interface Sci. 581(Pt A) (2021) 292-298.
