(216b) Tunable Parameters of Switchable Hydrophilicity Solvents

The promise of switchable solvents as green solvent alternatives lies in the ability to drastically alter their properties based on an external trigger. Switchable hydrophilicity solvents such as N,N‑Dimethylcyclohexylamine, DMCHA, are known to change properties based on both CO₂-addition as well as variations in temperature, both in the presence of water. While the impact of temperature has been observed via changes in water solubility, the solvent properties underlying these observations have not been quantified. Kamlet‑Taft solvatochromic parameters (α, β, and π*) and dielectric constants for SHS and SHS‑water mixtures were measured across a temperature range of 25˚C to 60˚C. Temperature‑swing effects of SHS in addition to CO₂ switching capabilities were validated and quantified on the Kamlet‑Taft polarity scale. Notably, binary mixtures of water in SHS show promising tunability in terms of its β and π* parameters induced by moderate variations in temperature. These properties – CO₂-switchability and temperature-tunability – have great potential for application in selective and more sustainable extractions.