Synergistic structures in lyotropic lamellar gels

Area of Science:

• Soft Matter Physics
• Materials Science
• Supramolecular Chemistry

Background:

• Lyotropic liquid crystals exhibit anisotropy.
• Physical gels provide mechanical stability.
• Combining these properties creates novel soft materials.

Purpose of the Study:

• To systematically study the microstructure of soft materials combining lyotropic liquid crystals and physical gels.
• To characterize the lyotropic lamellar phase (Lα) gelled with two distinct organogelators: 1,3:2,4-dibenzylidene-d-sorbitol (DBS) and 12-hydroxyoctadecanoic acid (12-HOA).
• To understand the structural differences induced by the different gelators.

Main Methods:

• Systematic small-angle neutron (SANS) and X-ray (SAXS) scattering experiments.
• Characterization of the D2O - n-decanol - SDS system in its lamellar phase (Lα).
• Comparison of gelator-free Lα phase with Lα phases gelled by DBS and 12-HOA.

Main Results:

• A pronounced shoulder appeared in scattering curves for the 12-HOA gelled lamellar phase.
• Scattering curves for the DBS-gelled Lα phase showed minimal change compared to the gelator-free system.
• The 12-HOA gelled system exhibited a synergistic structure, absent in the gelator-free or DBS-gelled systems.

Conclusions:

• The synergistic structure in 12-HOA gelled systems likely arises from minimizing elastic free energy.
• Lamellar layers may form cylindrical enclosures around larger 12-HOA gel fibers (25-30 nm) to prevent unfavored layer ends.
• These observed structures resemble myelin sheath formations around neural cell axons.