Hierarchical Emulsion Structure and Functionality Regulated by Coexisting Bicontinuous Microemulsion and Liquid...

Area of Science:

• Colloid and Surface Science
• Materials Science
• Cosmetic Science

Background:

• Microemulsions, typically low viscosity, require enhanced rheological properties for industrial use.
• Thickening bicontinuous microemulsions (BCMEs) without structural disruption or emulsifying oils with BCMEs is challenging.
• Existing oil-in-water emulsions often rely on crystalline lamellar gel networks, differing from the proposed mechanism.

Purpose of the Study:

• To develop a novel technique for creating thickened oil-in-water emulsions.
• To stabilize emulsions using coexisting bicontinuous microemulsion (BCME) and liquid crystal (LC) phases.
• To investigate the structural properties and thickening mechanisms of these novel emulsions.

Main Methods:

• Development of the BCLC emulsification technique.
• Structural analysis using small- and wide-angle X-ray scattering (SWAXS).
• Microscopic examination via freeze fracture transmission electron microscopy (FF-TEM) and scanning electron assisted dielectric microscopy (SE-ADM).

Main Results:

• The BCLC technique successfully produced nonfluidic, jelly emulsions.
• Structural analysis confirmed control over bending elasticity and BCME domain order.
• Submicrometer oil droplets were stabilized by LC networks, forming spongy or network-like patterns.

Conclusions:

• The BCLC emulsification technique offers a method to enhance microemulsion viscosity without compromising functionality.
• The resulting jelly emulsions exhibit improved usability and high cleansing performance, suitable for cosmetics.
• The thickening mechanism involves LC networks supporting oil droplets, distinct from traditional lamellar gel stabilization.