Understanding Differential Interaction of Protic and Aprotic Ionic Liquids inside Molecular Confinement

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Chemistry

Background:

• Ionic liquids (ILs) are explored as reaction media and drug carriers.
• Water-free reverse micelles (RMs) offer unique properties for these applications.
• Understanding IL-surfactant interactions is crucial for RM design.

Purpose of the Study:

• Synthesize and characterize two IL-based RMs: protic [NMP][Hex] and aprotic [Chl][Hex].
• Investigate the differential interionic interactions influencing RM properties.
• Correlate computational findings with experimental observations.

Main Methods:

• Synthesis of protic and aprotic ionic liquids.
• Formation of IL-in-oil reverse micelles with Tween-80 and cyclohexane.
• Phase behavior, Dynamic Light Scattering (DLS), and rheological studies.
• Density Functional Theory (DFT) calculations, including NBO analysis.
• Fourier-Transform Infrared Spectroscopy (FTIR) and time-resolved fluorescence.

Main Results:

• Successful formation of IL-in-oil RMs confirmed by phase behavior and DLS.
• [NMP][Hex]-based RMs showed larger monophasic regions, droplet sizes, and higher viscosity.
• DFT calculations indicated stronger [NMP]+-Tween-80 interactions due to protic nature.
• Experimental data (FTIR, fluorescence) supported the enhanced interactions in [NMP][Hex] systems.
• Both systems demonstrated efficient thermal stability.

Conclusions:

• Protic [NMP][Hex] ionic liquids form more stable and viscous RMs compared to aprotic [Chl][Hex].
• Interionic interactions, particularly hydrogen bonding, significantly influence RM properties.
• These novel IL-based RMs show promise for drug delivery and nanomaterial synthesis.