Capillary assembly of microscale ellipsoidal, cuboidal, and spherical particles at interfaces

Area of Science:

• Colloid and Surface Science
• Soft Matter Physics
• Materials Science

Background:

• Micron-sized anisotropic particles at fluid interfaces deform the interface due to their shape.
• This deformation creates excess interfacial area, leading to interactions that minimize energy.
• Understanding these interactions is crucial for controlling colloidal assembly and material properties.

Purpose of the Study:

• To systematically investigate interface deformations around single ellipsoidal and cuboidal particles.
• To correlate deformations with capillary bond energies and quantify particle interactions.
• To explore how anisotropic particle shape influences self-assembly via capillary forces.

Main Methods:

• Numerical simulations of interface deformations around ellipsoidal and cuboidal particles.
• Analysis of contact angles and particle aspect ratios.
• Characterization of capillary bond energies and interaction power laws.

Main Results:

• Interface deformations and interactions are weaker for cuboidal particles compared to ellipsoidal particles.
• Side-by-side orientation shows the most stable bound state; tip-to-side is repulsive.
• Capillary attraction between spherical and ellipsoidal particles suggests cluster formation and explains phenomena like coffee-ring effect suppression.

Conclusions:

• Near-field interaction calculations complement far-field studies for predicting colloidal assembly.
• Particle shape significantly impacts self-assembly behavior and stability of structures.
• Findings provide insights into controlling rheological properties of particle-laden interfaces.