Ether functionalisation, ion conformation and the optimisation of macroscopic properties in ionic liquids

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Chemistry

Background:

• Ionic liquids offer desirable properties like conductivity and stability.
• High viscosity hinders widespread application of ionic liquids.
• Understanding structure-property relationships is key to designing better ionic liquids.

Purpose of the Study:

• To investigate how molecular structure variations affect ionic liquid transport properties.
• To establish structure-property correlations for designing low-viscosity ionic liquids.
• To explore the impact of cation and anion modifications on ionic liquid fluidity.

Main Methods:

• Systematic variation of molecular structures in 16 ionic liquids.
• Utilizing ab initio calculations to link molecular structure to properties.
• Analyzing transport properties in relation to thermal and structural characteristics.

Main Results:

• Ether vs. alkyl side chains' impact on properties is mainly due to minimum energy geometries.
• Anion conformational flexibility shows unprecedented correlations with transport properties.
• Fluidity enhancement depends on anion flexibility when modifying cations with ether chains and phosphonium centers.

Conclusions:

• Targeted design of functional groups can yield ionic liquids with exceptionally high fluidity.
• Structure-property relationships provide a roadmap for designing task-specific ionic liquids.
• Modifications in cation and anion structures offer tunable control over ionic liquid transport properties.