Catastrophic thermal destabilization of two-dimensional close-packed emulsions due to synchronized coalescence initiation

Creep and drainage in the fast destabilization of emulsions Creep and drainage in the fast destabilization of emulsions

The destabilization of emulsions is important for many applications but remains incompletely understood. We perform squeeze flow measurements on oil-in-water emulsions, finding that the spontaneous destabilization of emulsions is generally very slow under normal conditions, with a characteristic time scale given by the drainage of the continuous phase and the coalescence of the dispersed phase. We show that if the emulsion is compressed between two plates, the destabilization can be sped up significantly; on the one hand, the drainage is faster due to the application of the squeezing force. On…

Emulsion Destabilization by Squeeze Flow

There is a large debate on the destabilization mechanism of emulsions. We present a simple technique using mechanical compression to destabilize oil-in-water emulsions. Upon compression of the emulsion, the continuous aqueous phase is squeezed out, while the dispersed oil phase progressively deforms from circular to honeycomb-like shapes. The films that separate the oil droplets are observed to thin and break at a critical oil/water ratio, leading to coalescence events. Electrostatic interactions and local droplet rearrangements do not determine film rupture. Instead, the destabilization occur…

Destabilization and phase separation of particle suspensions in emulsions

Yield stress fluids are widely used in industrial application to arrest dense solid particles, which can be studied by using a concentrated emulsion as a model fluid. We show in experiments that particle sedimentation in emulsions cannot be predicted by the classical criterion for spheres embedded in a yield stress fluid. Phase separation processes take place, where a liquid layer forms and particle sedimentation is enhanced by the emulsion drainage. In addition, emulsion drainage can be arrested or enhanced by the amount of particles embedded in the emulsion. A minimal mathematical model is d…

Field-Induced Breakup of Emulsion Droplets Stabilized by Colloidal Particles

We simulate the response of a particle-stabilized emulsion droplet in an external force field, such as gravity, acting equally on all $N$ particles. We show that the field strength required for breakup (at fixed initial area fraction) decreases markedly with droplet size, because the forces act cumulatively, not individually, to detach the interfacial particles. The breakup mode involves the collective destabilization of a solidified particle raft occupying the lower part of the droplet, leading to a critical force per particle that scales approximately as $N^{-1/2}$.

Effects of complex internal structures on rheology of multiple emulsions through a generalized boundary integral method

As fine templates to prepare microcapsules, multiple emulsions with complex internal structures have been generated through microfluidics. To study effects of layers, inner droplets and asymmetry of internal structures on rheology of multiple emulsions, a generalized boundary integral method is developed to investigate multiple emulsions with orderly structures up to n layers and up to mi droplets in the i-th layer. Under a modest extensional flow, the complication of internal structures and the collision among inner droplets will subject the particle to stronger shears. However, the particle …

双重乳液的冻结诱导拓扑转变

Freezing-induced topological transition of double-emulsion

本文研究W/O/W双重乳液的冻结过程，发现包裹油滴由外向内冻结会对内部水滴施加张力，引发从W/O/W到O/W的拓扑转变，并确定内部液滴临界尺寸约为19 μm，低于该尺寸时双重乳液保持稳定。