PEG-in-PDMS drops stabilised by soft silicone skins as a model system for elastocapillary emulsions with explicit...

Area of Science:

• Materials Science
• Colloid and Surface Science
• Polymer Chemistry

Background:

• Traditional macro-emulsions are limited by high interfacial energies (capillarity), restricting morphological control to a narrow range.
• Interfacial tension dictates the structure of conventional emulsions, offering limited tunability.

Purpose of the Study:

• To demonstrate explicit control over a wider range of emulsion morphologies using "elastocapillary emulsions".
• To investigate the simultaneous action of interfacial elasticity and interfacial tension in controlling emulsion structure.

Main Methods:

• Developed a model system of polyethylene glycol (PEG)-in-polydimethylsiloxane (PDMS) emulsions.
• Utilized a catalyst to cross-link reactive silicone polymers within the PDMS matrix, forming a gel layer on PEG drop surfaces.
• Employed in-flow chemistry in a millifluidic circuit to produce emulsions with controlled elastocapillary interfaces.

Main Results:

• Achieved interfaces spanning the full range of elastocapillary properties.
• Demonstrated the generation of diverse emulsion morphologies based on the dominance of capillarity versus elasticity.
• Characterized gel cross-linking and skin growth kinetics at the interface.

Conclusions:

• Findings advance the fundamental understanding of emulsion morphology with complex interfaces.
• The developed method is important for designing polymerised High Internal Phase Emulsions (polyHIPEs) with unique structure/property relationships.
• This approach is valuable for engineering silicone capsules with precisely tuned mechanical properties.