Our study "A structural underpinning of the lower critical solution temperature (LCST) behavior behind temperature-switchable liquids" has been published in Matter! The study is a collaboration with Applied Physics and The University of Alabama.
Temperature swing solvent extraction, TSSE, is an emerging desalination technology. While TSSE has been demonstrated for a variety of high-salinity desalination applications, the molecular-level mechanisms of the technique are poorly understood. This study investigates the governing phenomena underpinning the working principles of TSSE. Specifically, we examine the lower critical solution temperature (LCST) behavior of temperature-switchable amines employed in the technology. We integrate state-of-the-art X-ray scattering and molecular dynamics to shed light on the short- and long-range structures adopted by water and the amine solvents. The investigation shows that when water is initially introduced into the amine solvent, well-defined amine-water adduct pairs are formed. Interestingly, when more water is added to the system, nanoscale clusters of primarily water were observed. These insights shed light on the unusual temperature-switchable behavior of the amine-water mixture and, for the first time, provide direct experimental evidence of the entropy-lowering molecular cluster formation hypothesized as necessary for LCST behavior.
