Evolution of microscopic heterogeneity and dynamics in choline chloride-based deep eutectic solvents

Area of Science:

• Materials Science
• Physical Chemistry
• Chemical Engineering

Background:

• Deep eutectic solvents (DESs) are versatile non-aqueous solvents with potential in biomass processing and energy storage.
• Understanding the structure-property relationships in DESs is crucial for optimizing their applications.
• Glycerol and ethylene glycol-based DESs, like Glyceline and Ethaline, serve as model systems for fundamental studies.

Purpose of the Study:

• To investigate the impact of choline chloride addition on the structure and dynamics of model DESs (Glyceline and Ethaline).
• To establish correlations between microscopic structural changes and macroscopic properties of DESs.
• To provide a predictive understanding for designing tunable DESs.

Main Methods:

• Utilized a combination of computational (e.g., molecular dynamics) and experimental techniques.
• Studied DESs across multiple length scales (molecular to macroscopic) and time scales (picoseconds to seconds).
• Analyzed the evolution of structure and dynamics upon systematic addition of choline chloride.

Main Results:

• Choline chloride addition induces microscopic heterogeneities in the DES.
• These heterogeneities alter the primary structural relaxation dynamics of the parent solvents (glycerol and ethylene glycol).
• New dynamic modes emerge, showing strong correlations with the macroscopic properties of the formed DES.

Conclusions:

• The local structure and dynamics of DESs are significantly influenced by the systematic addition of components like choline chloride.
• Microscopic heterogeneities play a key role in determining the macroscopic properties of DESs.
• This study provides fundamental insights for the rational design and application of tunable DESs.