Mechanical stability of particle-stabilized droplets under micropipette aspiration

TL;DR

This study examines how particle-stabilized droplets respond mechanically to micropipette aspiration, revealing a two-stage failure process influenced by particle type and surface tension, with implications for droplet stability.

Contribution

It provides new insights into the mechanical response and failure mechanisms of particle-stabilized droplets under aspiration, highlighting the role of particle shape and surface chemistry.

Findings

Particles alter the failure mechanism but only modestly increase strength.

Droplets with surfactant are weaker than bare droplets.

Critical pressure is determined by fluid surface tension.

Abstract

We investigate the mechanical behavior of particle-stabilized droplets using micropipette aspiration. We observe that droplets stabilized with amphiphilic dumbbell-shaped particles exhibit a two-stage response to increasing suction pressure. Droplets first drip, then wrinkle and buckle like an elastic shell. While particles have a dramatic impact on the mechanism of failure, the mechanical strength of the droplets is only modestly increased. On the other hand, droplets coated with the molecular surfactant Sodium Dodecyl Sulfate are even weaker than bare droplets. In all cases, the magnitude of the critical pressure for the onset of instabilities is set by the fluid surface tension.