Supramolecular gels: using an amide-functionalized imidazolium-based surfactant.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Soft Matter Physics

Background:

• Supramolecular gel aggregates are formed through non-covalent interactions.
• Gelator-solvent and gelator-salt interactions significantly influence supramolecular gel properties.
• Existing research in this field is still in its nascent stages.

Purpose of the Study:

• To tune the formation conditions and properties of supramolecular gels.
• To investigate the effect of solvents and inorganic salts on gel behavior.
• To explore stimuli-responsive phase transitions and morphological changes in gels.

Main Methods:

• Utilized a low-molecular-weight gelator (LMWG): N-cetyl-N'-acetamido imidazolium bromide ([N-C16, N'-CONH2-Im]Br).
• Investigated gel formation in various solvents, including formamide (FM), with inorganic salt additives.
• Applied chemical (Cu2+/H2O2) and physical (temperature) stimuli to induce gel-sol transitions.
• Characterized gel morphology and structure using Small-angle X-ray scattering (SAXS).

Main Results:

• Achieved gel-sol phase transition under chemical and physical stimuli in a 2 wt% [N-C16, N'-CONH2-Im]Br gel in formamide.
• Observed enhanced mechanical strength and morphological changes from straight stripes to curly belts upon addition of CuBr2.
• SAXS measurements confirmed the presence of bilayer units with interdigitated hydrocarbon tails.
• Identified π-π interaction, H-bonding, and hydrophobic interactions as key driving forces for gelation.

Conclusions:

• The developed low-cost gelator allows for facile preparation and coordination-driven assembly.
• The robust supramolecular gel exhibits stimuli-responsive behavior and tunable properties.
• Potential applications include use as material templates and in drug delivery systems.