Assessing Melting and Solid-Solid Transition Properties of Choline Chloride via Molecular Dynamics Simulations

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• Choline chloride (ChCl) is a key hydrogen bond donor in deep eutectic solvents (DESs).
• Experimental determination of ChCl melting properties is difficult due to decomposition, resulting in inconsistent literature values.
• Accurate melting properties are essential for characterizing the solid-liquid phase behavior of ChCl-based DESs.

Purpose of the Study:

• To compute the phase transitions of choline chloride (ChCl) using molecular dynamics simulations.
• To evaluate the influence of different atomistic force fields on the simulated melting properties of ChCl.
• To propose reliable melting properties for ChCl, aiding DES research.

Main Methods:

• Utilized molecular dynamics (MD) simulations to model ChCl.
• Tested multiple atomistic force fields to assess their impact on simulation accuracy.
• Calculated melting temperature and enthalpy through phase transition analysis.

Main Results:

• Simulated melting temperature of ChCl is 627 K.
• Simulated melting enthalpy of ChCl is 7.8 kJ/mol.
• Results demonstrated sensitivity to the chosen force field, with specific values showing good agreement with select literature data.

Conclusions:

• The study proposes 627 K and 7.8 kJ/mol as the most likely melting properties for choline chloride (ChCl).
• These findings provide valuable data for the design and application of ChCl-containing deep eutectic solvents (DESs).
• Further experimental validation is recommended due to the tentative nature of the results, stemming from limited data for liquid ChCl.