Complex by design: Hydrotrope-induced micellar growth in deep eutectic solvents

Area of Science:

• Colloid and Surface Science
• Supramolecular Chemistry
• Materials Science

Background:

• Ionic surfactant self-assembly in deep eutectic solvents (DES) is a recent advancement.
• The solvophobic effect drives micelle formation in DES, with specific ion interactions influencing structure.
• Hydrotropic salts are hypothesized to significantly alter micellar structure in DES, promoting worm-like aggregates.

Purpose of the Study:

• To investigate the effect of hydrotropic salts on surfactant micelle formation in deep eutectic solvents.
• To understand how hydrotrope-surfactant interactions influence micelle morphology.
• To explore the potential for controlling self-assembly in DES.

Main Methods:

• Systematic investigation of hydrotrope-surfactant assemblies in neat and hydrated 1:2 choline chloride:glycerol.
• Utilized contrast variation small-angle neutron scattering (SANS) to probe micellization.
• Examined the effect of varying hydrotrope-to-surfactant ratios.

Main Results:

• First investigation of salt-induced micellar growth in DES.
• Observed significant micelle elongation due to hydrotrope-micelle interactions in DES.
• Demonstrated the formation of worm-like micelles with tunable morphology and flexibility via hydrotrope condensation.

Conclusions:

• Hydrotrope condensation on micelles alters monomer packing, leading to worm-like structures.
• Micelle morphology in DES can be controlled through specific surfactant-salt interactions.
• Presents new avenues for self-assembly and co-assembly in neoteric solvents.