Related Experiment Video
Updated: Oct 25, 2026

Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature
Published on: December 20, 2016
Weak Anion Hydration Drives LCST Behavior in Ionic Liquid-Water Mixtures: Insights from Calorimetry and Neutron
Sanskrita Madhukailya1, Guillaume Depraetère2, Nithavong Cam2
1The QUILL Research Centre, School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, BelfastBT9 5AG, U.K.
Abstract:
Isothermal titration calorimetry (ITC) combined with neutron diffraction and isotopic substitution (NDIS) has been used to elucidate the molecular origins of lower critical solution temperature (LCST) behavior in the tetrabutylphosphonium 5-phenyltetrazolate/water ([P4444][Ph-tet]/H2O) system. Comparison with the structurally similar but fully water-miscible analogue, tetrabutylphosphonium benzoate ([P4444][Bz]) reveals a much smaller negative enthalpy of mixing with water. This is indicative that weaker solvation of the [Ph-tet]- anion drives an entropy-dominated desolvation process upon heating, leading to phase separation into IL-rich and water-rich domains and is supported by observation from NDIS that the [Ph-tet]- anion is only weakly hydrated by water.
Related Concept Videos
Aqueous Solutions and Heats of Hydration
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
Intermolecular Forces
Theory of Strong Electrolytes
Ionic Association
Trends in Lattice Energy: Ion Size and Charge
Ionic Strength: Effects on Chemical Equilibria
In this solution, the primary cation—the calcium...

