Hydrogel Formation by Glutamic-acid-based Organogelator Using Surfactant-mediated Gelation.

Area of Science:

• Materials Science
• Supramolecular Chemistry

Background:

• Low-molecular-weight gelators form hydrogels with stimuli-responsive properties, useful in cosmetics and drug delivery.
• Novel gelator development is challenging due to sensitivity to molecular architecture.
• Organogelators, insoluble in water, have not been explored for hydrogel formation.

Purpose of the Study:

• To investigate the surfactant-mediated gelation of organogelators for hydrogel formation.
• To explore the use of glutamic acid-based organogelators in hydrogel synthesis.
• To characterize the self-assembled structures and thermomechanical properties of the resulting hydrogels.

Main Methods:

• Solubilizing 1:1 mixtures of N-lauroyl-L-glutamic acid dibutylamide and N-2-ethylhexanoyl-L-glutamic acid dibutylamide in aqueous surfactant solutions.
• Utilizing anionic (sodium lauroyl glutamate) and cationic (cetyltrimethylammonium chloride) surfactants.
• Varying the molar fraction of cetyltrimethylammonium chloride to control micelle morphology (spherical vs. wormlike).

Main Results:

• Hydrogels formed with a minimum gelation concentration of ~0.2-0.6 wt%.
• Spherical and wormlike micelles were formed by adjusting surfactant composition, influencing hydrogel properties.
• Hydrogels with wormlike micelles exhibited higher sol-gel transition temperatures and formed fibrillar networks.
• Hydrogels with spherical micelles were elastic, while those with wormlike micelles were viscoelastic.
• Organogelator networks maintained elastic properties at elevated temperatures, showing spontaneous bundling and cross-linking.

Conclusions:

• Surfactant-mediated gelation is a viable method for creating hydrogels from water-insoluble organogelators.
• The morphology of self-assembled micelles dictates the viscoelastic properties and thermal stability of the hydrogels.
• Glutamic acid-based organogelators can form stable, temperature-resilient hydrogel networks with tunable properties.