Water Incorporation into Stearate Salts in Hydrophobic Deep Eutectic Solvents

Deep eutectic solvents (DES) are novel solvents comprised of naturally occurring compounds, which are non-toxic, sustainable and highly tuneable. They are mixtures which due to strong interactions between a hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA), cause a melting point depression allowing them to be liquids at room temperature. DES based on carboxylic acids with menthol are hydrophobic, so they are used to extract hydrophobic actives from biomass and dissolve poorly water soluble therapeutics. These solutions are now being probed as components of formulation systems for delivery of such solutes. We are studying viscosity modification and self-assembly in these hydrophobic DES via the addition low concentrations of stearate salts, namely sodium, calcium and magnesium. This experiment plans to investigate the self assembly of stearate salts in menthol based DES in the presence of small amounts of water. This will be achieved by using deuterated stearate species and D2O in DES with varied d- or h-dodecanoic acid content to observing stearate assembly and the effects of water on clustering in the presence of the different salt cations.