Partial Coalescence of Sessile Drops with Different Miscible Liquids

Borcia, Rodica; Bestehorn, Michael

doi:10.1021/la3050835

Cited by 21 publications

(22 citation statements)

References 27 publications

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“…Finally, one can solve the thickness of the thin film h by combining Eqs. (4) and (8). As anticipated, the various scaling laws are such that the thickness is independent of time…”

Section: Results and Scaling Lawssupporting

confidence: 56%

“…This slowing down is markedly different from the "delayed coalescence," observed when two sessile drops of miscible liquids come into contact. [6][7][8][9][10] Rather than coalescing, the drop of the larger surface tension was found to pull the other drop at constant velocity over the substrate. Such a constant velocity suggests that the surface tension gradient remains constant and localized where the two fluids meet, at least during the initial stages of the experiment.…”

Section: Discussionmentioning

confidence: 99%

“…When two miscible droplets of different chemical composition are brought into contact, the Marangoni forces can delay or prevent actual coalescence. [6][7][8][9][10] The coalescence is frustrated by the very localized gradient of surface tension in the "neck" region. In contrast to the growth of the neck as in normal coalescence, [11][12][13][14] the drops exhibit a translational motion where the drop of larger surface tension pulls the other drop over the substrate.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Marangoni spreading due to a localized alcohol supply on a thin water film

2015

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Bringing two miscible fluids into contact naturally generates strong gradients in surface tension. Here, we investigate such a Marangoni-driven flow by continuously supplying isopropyl alcohol (IPA) on a film of water, using micron-sized droplets of IPA-water mixtures. These droplets create a localized depression in surface tension that leads to the opening of a circular, thin region in the water film. At the edge of the thin region, there is a growing rim that collects the water of the film, reminiscent of Marangoni spreading due to locally deposited surfactants. In contrast to the surfactant case, the driving by IPA-water drops gives rise to a dynamics of the thin zone that is independent of the initial layer thickness. The radius grows as r ∼ t 1/2 , which can be explained from a balance between Marangoni and viscous stresses. We derive a scaling law that accurately predicts the influence of the IPA flux as well as the thickness of the thin film at the interior of the spreading front. C 2015 AIP Publishing LLC. [http://dx.

show abstract

“…Finally, one can solve the thickness of the thin film h by combining Eqs. (4) and (8). As anticipated, the various scaling laws are such that the thickness is independent of time…”

Section: Results and Scaling Lawssupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Marangoni spreading due to a localized alcohol supply on a thin water film

2015

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“…Karpitschka and Riegler observed that when two chemically different sessile droplets come within close contact of each other, they do not coalesce immediately but remain separated in a temporary state of noncoalesence. Based on hydrodynamic analyses of the phenomenon, Borcia and Bestehorn deliberated that the surface tension gradient causes Marangoni flow at the neck region where the two droplets are connected, eventually producing a temporary dewetting of states between the two droplets. Yerushalmi‐Rozen et al also reported that mixtures composed of two kinds of oligomers on a solid surface undergo phase separation which is driven by the difference in surface tension.…”

Section: Introductionmentioning

confidence: 99%

Underlying Mechanism of Inkjet Printing of Uniform Organic Semiconductor Films Through Antisolvent Crystallization

Noda

Minemawari

Matsui

et al. 2015

Adv Funct Materials

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An underlying mechanism is reported for the formation of highly uniform crystalline organic semiconductor fi lms by the double-shot inkjet printing (IJP) technique utilizing antisolvent crystallization. It is demonstrated that the ability to form uniform fi lms with this technique can be attributed to the unique nature of the initial contact dynamics between the chemically different microdroplets before occurrence of solute crystallization. Experiments are conducted systematically where a single microdroplet is over-deposited by the IJP technique on a chemically different sessile droplet, for ten kinds of pure and miscible solvent combinations. The subsequent behavior is observed by high speed camera. The initial contact dynamics can be classifi ed into three dramatically different cases that are respectively referred to as wetting, dewetting, and sinking. These phenomena are unique to microdroplets and the conditions for the occurrence of each type of phenomenon can be consistently explained by the fact that the initial contact dynamics are driven by the difference of surface tension of the liquids. Among the three kinds of dynamics, the wetting phenomenon creates a thin solution layer on the antisolvent droplet surface and can be used thus to manufacture uniform semiconductor fi lms, where the coffee ring effect can be eliminated.

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“…The instability wavelength at the onset is λ o ≈ 0.45 mm in figure 11 The driving forces of the coalescence and coarsening of the droplets are on the one hand a reduction of interfacial area and on the other hand differences in the overall species concentration in neighboring droplets. This concentration difference corresponds to a surface tension difference that causes the droplet with lower surface tension to flow towards the droplet with higher surface tension [70][71][72][73][74][75][76][77][78]. Since the concentration differences in neighboring droplets are very likely small, a coalescence delay [73][74][75][76][77][78] does not occur.…”

Section: Two-dimensional Simulationsmentioning

confidence: 99%