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Preparation of Binary and Ternary Deep Eutectic Systems
Published on: October 31, 2019
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Estimating the nonideality of eutectic systems containing thermally unstable substances
Ahmad Alhadid1, Christian Jandl2, Sahar Nasrallah1
1Biothermodynamics, TUM School of Life Sciences, Technical University of Munich, Freising, Germany.
The Journal of Chemical Physics
|September 6, 2023
Summary
This study presents a novel method to determine the activity coefficients of thermally unstable compounds in eutectic systems by analyzing cocrystal formation. This approach enables accurate modeling of solid-liquid equilibria (SLE) phase diagrams for such systems.
Area of Science:
- Materials Science
- Physical Chemistry
- Chemical Engineering
Background:
- Eutectic systems design relies on understanding solid-liquid equilibria (SLE).
- Accurate SLE modeling requires component melting properties and liquid phase activity coefficients.
- Thermally unstable substances pose challenges due to unavailable melting properties, hindering SLE phase diagram modeling.
Purpose of the Study:
- To evaluate liquid phase activity coefficients of thermally unstable compounds independent of their melting properties.
- To model SLE phase diagrams of eutectic systems containing thermally unstable substances.
- To investigate the interactions within liquid solutions of eutectic systems.
Main Methods:
- Correlating solid-liquid equilibria (SLE) data of cocrystals to calculate activity coefficients.
- Employing differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) to obtain SLE phase diagrams.
- Utilizing the non-random, two-liquid (NRTL) equation for activity coefficient calculations.
Main Results:
- Successfully obtained SLE phase diagrams for three eutectic systems: tetramethylammonium chloride/catechol, tetraethylammonium chloride/catechol, and betaine/catechol.
- Identified the formation of nine novel cocrystals within these systems.
- Calculated activity coefficients revealing substantial negative deviation from ideality, indicative of strong hydrogen bonding.
Conclusions:
- Developed a method to determine activity coefficients and model SLE phase diagrams for systems with thermally unstable components.
- Strong intermolecular interactions, specifically hydrogen bonding, were confirmed in the studied liquid solutions.
- Highlighting the importance of modeling ion-ion interactions for nonideality in ionic eutectic systems.
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