Using Contactless Interfacial Rheology to Probe Interfacial Mechanics for Compositional Ripening

Area of Science:

• Colloid and Interface Science
• Rheology
• Materials Science

Background:

• Interfacial rheology of colloidal systems is crucial for understanding emulsion stability and material properties.
• Poly(methyl methacrylate) (PMMA) colloids at oil-water interfaces are model systems for studying interfacial phenomena.
• Modifying interparticle interactions can significantly alter the macroscopic behavior of colloidal interfaces.

Purpose of the Study:

• To investigate the effect of modifying colloid-colloid interactions on the rheological properties of PMMA colloids at a dodecane-water interface.
• To understand how toluene addition influences interfacial behavior and emulsion stability.
• To examine the relationship between interparticle attractions and interfacial rheology.

Main Methods:

• Qualitative observation of water-in-oil emulsions during compositional ripening with and without toluene.
• Utilizing a contactless interfacial rheometry setup to measure interfacial properties.
• Characterizing the rheological response of PMMA colloid-laden interfaces with varying toluene concentrations.

Main Results:

• Toluene addition to the oil phase modified attractive interactions between PMMA colloids.
• Emulsion droplets transitioned from explosive rupture to forming connected colloidal structures upon toluene addition.
• The PMMA colloid-water-dodecane interface exhibited significantly weaker and more flexible rheological properties after toluene addition.

Conclusions:

• Contrary to expectations for increased attractions, toluene addition weakens the colloidal interface.
• Modifying interparticle interactions offers a route to tune interfacial rheology and emulsion stability.
• The findings provide insights into the complex interplay between interparticle forces and interfacial mechanics in colloidal systems.