Confining deep eutectic solvents in nanopores: Insight into thermodynamics and chemical activity

We have established the detailed phase diagram of prototypical deep eutectic solvent ethaline (ethylene glycol / choline chloride 2:1) as a function hydration level, in bulk state and confined nanochannels mesostructured porous silica matrices MCM-41 SBA-15, with pore radii RP = 1.8 nm 4.15 nm. For neat moderately hydrated DESs, freezing was avoided glassforming solutions were formed all cases. mass fraction water above threshold value Wg’ ≈ 30%, crystallization occurred led to formation maximally-freeze-concentrated DES solution. In this case, extremely melting depressions attained states, due combination confinement cryoscopic effects. These phenomena analyzed quantitatively, based on an extended version classical Gibbs-Thomson Raoult thermodynamic approaches. framework, predicted values chemical activity systems shown systematically deviate from those counterparts. The origin striking observation is discussed respect anomalies ‘no-man’s land’ probable existence specific nanostructures when manipulated or at interfaces solids.