Controlled jamming of particle-laden interfaces using a spinning drop tensiometer

Area of Science:

• Colloid and surface science
• Materials science
• Fluid dynamics

Background:

• Particles at fluid interfaces can form jammed monolayers, exhibiting solid-like properties.
• Interfacial jamming prevents morphological coarsening, stabilizing complex two-phase systems like nonspherical drops and bijels.

Purpose of the Study:

• To systematically investigate interfacial tension-driven jamming of particle monolayers.
• To understand the relationship between particle concentration, interfacial area, and jamming behavior.
• To explore the influence of different fluid interfaces on jamming phenomena.

Main Methods:

• Utilized a spinning drop tensiometer (SDT) to study particle-covered mineral oil drops in ethylene glycol.
• Controlled drop retraction by adjusting rotational speed, thereby altering interfacial area and particle concentration.
• Analyzed the jamming transition and hysteresis during compression and expansion of the particle monolayer.

Main Results:

• Interfacial jamming arrested drop retraction when the specific interfacial area approached close packing.
• Fast contraction or low particle loading resulted in less compact jammed monolayers.
• Significant hysteresis was observed, indicating a minimum stress is needed for unjamming.
• Different behavior was noted at a mineral oil/silicone oil interface, suggesting interparticle attraction dominates nonpolar systems.

Conclusions:

• Particle monolayers at fluid interfaces exhibit jamming, arresting morphological changes.
• Jamming behavior is sensitive to interfacial area, particle loading, and interface type.
• The study provides insights into the mechanics and stability of particle-stabilized interfaces.