Design of Deep Eutectic Systems: Plastic Crystalline Materials as Constituents

Area of Science:

• Materials Science
• Physical Chemistry
• Green Chemistry

Background:

• Deep eutectic solvents (DESs) are tunable, environmentally friendly solvents formed from low-melting-point constituents.
• Plastic crystalline materials (PCs), with their ordered yet disordered structures, are potential candidates for DES formation.
• Understanding the behavior of PCs as DES components is crucial for developing new solvent systems.

Purpose of the Study:

• To investigate the potential of plastic crystalline materials (PCs) as constituents for deep eutectic solvents (DESs).
• To characterize the thermal properties and phase diagrams of eutectic systems involving specific PCs.
• To evaluate the non-ideality and melting point depression in these novel DES systems.

Main Methods:

• Differential scanning calorimetry (DSC) was used to study solid-plastic transitions and melting properties of pure PCs.
• Solid-liquid equilibrium phase diagrams were experimentally measured for four distinct eutectic systems.
• Analysis of eutectic point depression was performed to assess system non-ideality.

Main Results:

• Three PCs (neopentyl alcohol, pivalic acid, neopentyl glycol) were successfully utilized as DES constituents.
• The studied eutectic systems, despite near-ideal behavior, exhibited substantial melting point depressions.
• Observed depressions were comparable to or exceeded those in strongly non-ideal eutectic systems.

Conclusions:

• Plastic crystalline materials can serve as effective components in forming deep eutectic solvents.
• The formation of DESs from PCs is feasible even in systems exhibiting ideal or near-ideal behavior.
• These findings expand the scope of DES constituents and offer new avenues for green solvent design.