Delayed coalescence of surfactant containing sessile droplets

@article{Bruning2018DelayedCO,
  title={Delayed coalescence of surfactant containing sessile droplets},
  author={Myrthe A Bruning and Maxime Costalonga and Stefan Karpitschka and Jacco H. Snoeijer},
  journal={Physical Review Fluids},
  year={2018}
}
When two sessile drops of the same liquid touch, they merge into one drop, driven by capillarity. However, the coalescence can be delayed, or even completely stalled for a substantial period of time, when the two drops have different surface tensions, despite being perfectly miscible. A temporary state of non-coalescence arises, during which the drops move on their substrate, only connected by a thin neck between them. Existing literature covers pure liquids and mixtures with low surface… 

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References

SHOWING 1-10 OF 29 REFERENCES

Quantitative experimental study on the transition between fast and delayed coalescence of sessile droplets with different but completely miscible liquids.

It is found that the coalescence mode depends predominantly on the differences in the surface tensions of the two droplets, and within the investigated parameter space, the transition seems independent from droplet size, absolute values of thesurface tensions, and viscosity.

Coalescence of spreading droplets on a wettable substrate.

The coalescence dynamics of two spreading droplets on a highly wettable substrate is investigated and the scaling behavior is demonstrated to be consistent with a model in which the growth of the meniscus bridge is governed by the viscously hindered flux from the droplets.

Noncoalescence of sessile drops from different but miscible liquids: hydrodynamic analysis of the twin drop contour as a self-stabilizing traveling wave.

A thin film hydrodynamic analysis of the observed moving twin drop configuration, where two separate drop bodies, connected by a thin liquid neck, move over the substrate, induces a local surface flow that stabilizes a traveling wave.

Influence of droplet geometry on the coalescence of low viscosity drops.

A geometric model is presented that quantitatively captures the transition from 2/3 to 1/2 exponent, and unifies the inertial coalescence of sessile drops and freely suspended drops.

Dynamic drying in the early-stage coalescence of droplets sitting on a plate

The early-stage coalescence of two sessile drops is investigated theoretically and experimentally. The coalescence of small sessile drops of diethylene glycol on silicon wafer is induced either by

Symmetric and asymmetric coalescence of drops on a substrate.

It is shown that the universal shape of the bridge is accurately described by similarity solutions of the one-dimensional lubrication equation, and predicts that, once the drops are connected on a microscopic scale, the bridge grows linearly in time with a strong dependence on the contact angles.

Sharp transition between coalescence and non-coalescence of sessile drops

Abstract Unexpectedly, under certain conditions, sessile drops from different but completely miscible liquids do not always coalesce instantaneously upon contact: the drop bodies remain separated in

Inertial coalescence of droplets on a partially wetting substrate

We consider the growth rate of the height of the connecting bridge in rapid surface-tension-driven coalescence of two identical droplets attached on a partially wetting substrate. For a wide range of

Vapour-mediated sensing and motility in two-component droplets

Two-component droplets of well-chosen miscible liquids such as propylene glycol and water deposited on clean glass are not subject to pinning and cause the motion of neighbouring droplets over a distance, unlike the canonical predictions for these liquids on a high-energy surface, these droplets do not spread completely but exhibit an apparent contact angle.

Spontaneous Spreading of Surfactant Solutions on Hydrophilic Surfaces: CnEm in Ethylene and Diethylene Glycol

The spontaneous spreading of solutions of nonionic CnEm surfactants in ethylene and diethylene glycol on hydrophilic surfaces is investigated. The parameters of the study are the relative