Self‐Sustained Marangoni Flows Driven by Chemical Reactions

Nguindjel, Anne‐Déborah C.; Korevaar, Peter A.

doi:10.1002/syst.202100038

Cited by 6 publications

(6 citation statements)

References 50 publications

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“…Collective behavior that emerges from Marangoni flow-based systems offers an attractive pathway to establish self-organization of elements that move individually. The Marangoni effect drives a liquid to flow from regions with low surface tension to those with high surface tension. − Upon release of a surface-active compound, floating objects can initiate Marangoni flows in the surrounding fluid, such that the objects repel each other and self-organize into a pattern. In the case of a liquid droplet immersed in water, a surfactant that is absorbed or generated at the droplet interface generates a difference in interfacial tension between the front and rear of the droplet.…”

Section: Introductionmentioning

confidence: 99%

Self-Organization Emerging from Marangoni and Elastocapillary Effects Directed by Amphiphile Filament Connections

Winkens¹,

Korevaar²

2022

Langmuir

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Self-organization of meso- and macroscale structures is a highly active research field that exploits a wide variety of physicochemical phenomena, including surface tension, Marangoni flow, and (elasto)capillary effects. The release of surface-active compounds generates Marangoni flows that cause repulsion, whereas capillary forces attract floating particles via the Cheerios effect. Typically, the interactions resulting from these effects are nonselective because the gradients involved are uniform. In this work, we unravel the mechanisms involved in the self-organization of amphiphile filaments that connect and attract droplets floating at the air–water interface, and we demonstrate their potential for directional gradient formation and thereby selective interaction. We simulate Marangoni flow patterns resulting from the release and depletion of amphiphile molecules by source and drain droplets, respectively, and we predict that these flow patterns direct the growth of filaments from the source droplets toward specific drain droplets, based on their amphiphile depletion rate. The interaction between such droplets is then investigated experimentally by charting the flow patterns in their surroundings, while the role of filaments in source–drain attraction is studied using microscopy. Based on these observations, we attribute attraction of drain droplets and even solid objects toward the source to elastocapillary effects. Finally, the insights from our simulations and experiments are combined to construct a droplet-based system in which the composition of drain droplets regulates their ability to attract filaments and as a consequence be attracted toward the source. Thereby, we provide a novel method through which directional attraction can be established in synthetic self-organizing systems and advance our understanding of how complexity arises from simple building blocks.

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Section: Introductionmentioning

confidence: 99%

Self-Organization Emerging from Marangoni and Elastocapillary Effects Directed by Amphiphile Filament Connections

Winkens¹,

Korevaar²

2022

Langmuir

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“…In a work recently published by our research group, the need for an external source of protons is eliminated upon using a photochemical reaction. 137 Starting from a homogeneous aqueous solution containing a photoacid generator and the surface active sodium oleate, a pH gradient is established upon local irradiation of the interface ( Fig. 10a ).…”

Section: Marangoni Flow Systemsmentioning

confidence: 99%

Spatial programming of self-organizing chemical systems using sustained physicochemical gradients from reaction, diffusion and hydrodynamics

Nguindjel

Visser

Winkens

et al. 2022

Phys. Chem. Chem. Phys.

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“…Via the Marangoni effect, sustained motion then manifests as (collective) self-propulsion of droplets or interfacial flow of liquids. [32][33][34][35][36][37][38] Similarly, collective, [39] self-propelled [40][41][42][43] and directed [44][45][46][47] motion has been observed when droplets convert empty micelles into filled ones, or are brought out of equilibrium by UV-irradiation or temperature changes. These concepts have been exploited to achieve functions such as chemo-and phototaxis, maze solving, multiphase reactors, collectively moving swarms, and reconfigurable structures.…”

Section: Introductionmentioning

confidence: 97%

Orbiting self-organization of filament-tethered surface-active droplets

Winkens

Vilcan

Visser

et al. 2022

Preprint

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Dissipative chemical systems operate outside of equilibrium, and hold potential to enable life-like behavior in synthetic matter, such as self-organization, motility, and dynamic switching between different states. Here, out-of-equilibrium self-organization is demonstrated at an air-water interface, enabled by amphiphile filaments that self-assemble from source droplets and tether to pivalic anhydride-based drain droplets, which are surrounded by a pivalic acid gradient due to their hydrolysis. The coupling of chemical gradients, self-assembly and Marangoni flow due to release and depletion of amphiphiles at the air-water interface generates a unique orbiting of drain droplets around the source droplet. This orbiting is proposed to be driven by the selective adhesion of filaments to the front of the moving drain, while filaments approaching the drain from behind are destabilized upon contact with the asymmetrical gradient of pivalic acid. The motion sustains itself to complete multiple rotations, ending when the depletion of amphiphiles at the drain, which drives the Marangoni flow towards the drain, becomes too weak to attract new filaments. Potential applications are foreseen in rearranging networks for dynamic transfer of chemical signals amongst interconnected droplets, and the implementation of dissipative chemical reactions in self-organizing systems as a strategy towards life-like behavior is highlighted.

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Self‐Sustained Marangoni Flows Driven by Chemical Reactions

Cited by 6 publications

References 50 publications

Self-Organization Emerging from Marangoni and Elastocapillary Effects Directed by Amphiphile Filament Connections

Self-Organization Emerging from Marangoni and Elastocapillary Effects Directed by Amphiphile Filament Connections

Spatial programming of self-organizing chemical systems using sustained physicochemical gradients from reaction, diffusion and hydrodynamics

Orbiting self-organization of filament-tethered surface-active droplets

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