Microstructure determination of AOT + phenol organogels utilizing small-angle X-ray scattering and atomic force...

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Physical Chemistry

Background:

• Organogels are materials that can encapsulate liquids within a solid network.
• Surfactants are molecules that can self-assemble into various structures in solution.
• Understanding the self-assembly of surfactants is crucial for designing novel materials.

Purpose of the Study:

• To investigate the formation and microstructure of organogels formed by bis(2-ethylhexyl) sulfosuccinate (AOT) and p-chlorophenol.
• To elucidate the role of nonpolar solvents in the self-assembly process.
• To characterize the molecular architecture of the resulting organogel.

Main Methods:

• Organogel formation using AOT and p-chlorophenol in various nonpolar solvents.
• Small-angle X-ray scattering (SAXS) for structural analysis.
• Tapping mode atomic force microscopy (AFM) for direct visualization.

Main Results:

• Organogels spontaneously form at a 1:1 AOT:phenol molar ratio in solvents like benzene, toluene, and alkanes.
• SAXS data reveal solvent-dependent characteristic length scales for AOT/phenol strands that self-assemble into fibers.
• AFM imaging confirms the organogel structure comprises aggregated fiber bundles.

Conclusions:

• The organogel structure is based on hydrogen-bonded AOT/phenol strands forming fibers, which then aggregate into bundles.
• A hierarchical molecular architecture with three distinct length scales (strands, fibers, bundles) is proposed.
• The solvent's chemical nature significantly influences the self-assembly and resulting gel properties.