Marangoni effect

About: Marangoni effect is a research topic. Over the lifetime, 5336 publications have been published within this topic receiving 98562 citations. The topic is also known as: Gibbs–Marangoni effect.

Autonomous mesoscale positioning emerging from myelin filament self-organization and Marangoni flows.

Abstract: Out-of-equilibrium molecular systems hold great promise as dynamic, reconfigurable matter that executes complex tasks autonomously. However, translating molecular scale dynamics into spatiotemporally controlled phenomena emerging at mesoscopic scale remains a challenge—especially if one aims at a design where the system itself maintains gradients that are required to establish spatial differentiation. Here, we demonstrate how surface tension gradients, facilitated by a linear amphiphile molecule, generate Marangoni flows that coordinate the positioning of amphiphile source and drain droplets floating at air-water interfaces. Importantly, at the same time, this amphiphile leads, via buckling instabilities in lamellar systems of said amphiphile, to the assembly of millimeter long filaments that grow from the source droplets and get absorbed at the drain droplets. Thereby, the Marangoni flows and filament organization together sustain the autonomous positioning of interconnected droplet-filament networks at the mesoscale. Our concepts provide potential for the development of non-equilibrium matter with spatiotemporal programmability. Buckling instabilities in amphiphile-based lamellar systems can lead to the formation of tubular fingers. Van der Weijden et al. show how to shepherd their growth and destination by using drain droplets that help establishing stable interconnected mesoscale droplet networks.

Long-Wavelength Marangoni Convection in a Liquid Layer with Insoluble Surfactant: Linear Theory

Abstract: The subject of this paper is the long-wave Marangoni convection in a horizontal liquid layer with insoluble surfactant absorbed on the free surface. The surfactant is convected by interfacial velocity field and diffuses over the interface but not into the bulk of the fluid. The layer is subjected to a transverse temperature gradient. The buoyancy effects are negligible as compared to the Marangoni forces. We consider both cases of flat nondeformable and deformable surface. The linear stability analysis of this system is performed. It is shown that in both cases of the upper surface monotonic and oscillatory modes exist. Convection thresholds are determined and the critical Marangoni numbers for monotonic as well as for oscillatory mode are obtained. It is shown that the monotonic long-wave instability is more dangerous than oscillatory one only for small elasticity numbers, if the Lewis number is small.

Novel pattern forming states for Marangoni convection in volatile binary liquids

Abstract: We describe experiments on Marangoni convection in thin evaporating liquid films. The films are binary mixtures of ethanol and water exposed to the ambient room air during all experimental runs. These experiments exhibit a variety of different, often novel, patterns, depending on the concentration (weight fraction) c of ethanol. Among these are mobile circular convective patterns, which have not been previously observed, to our knowledge. The convective patterns evolve due to the evaporation of both the solvent and the solute, and their size increases substantially with the initial concentration c. The patterns reported here differ from those found in binary mixtures of NaCl and water, where only water evaporates.

Collective dynamics of chemically active particles trapped at a fluid interface

Abstract: Chemically active colloids generate changes in the chemical composition of their surrounding solution and thereby induce flows in the ambient fluid which affect their dynamical evolution. Here we study the many-body dynamics of a monolayer of spherically symmetric active particles trapped at a fluid–fluid interface. To this end we consider a model for the large-scale spatial distribution of particles which incorporates the direct pair interaction (including also the capillary interaction which is caused specifically by the interfacial trapping) as well as the effect of hydrodynamic interactions (including the Marangoni flow induced by the response of the interface to the chemical activity). The values of the relevant physical parameters for typical experimental realizations of such systems are estimated and various scenarios, which are predicted by our approach for the dynamics of the monolayer, are discussed. In particular, we show that the chemically-induced Marangoni flow can prevent the clustering instability driven by the capillary attraction.