A viscous switch for liquid-liquid dewetting

A M J Edwards,R Ledesma-Aguilar,C V Brown,M I Newton,G Mchale

doi:10.1038/s42005-020-0284-8

A M J Edwards, R Ledesma-Aguilar + Show 3 more

Open Access

https://doi.org/10.1038/s42005-020-0284-8

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Abstract

The spontaneous dewetting of a liquid film from a solid surface occurs in many important processes, such as printing and microscale patterning. Experience suggests that dewetting occurs faster on surfaces of higher film repellency. Here, we show how, unexpectedly, a surrounding viscous phase can switch the overall dewetting speed so that films retract slower with increasing surface repellency. We present experiments and a hydrodynamic theory covering five decades of the viscosity ratio between the film and the surrounding phase. The timescale of dewetting is controlled by the geometry of the liquid-liquid interface close to the contact line and the viscosity ratio. At small viscosity ratio, dewetting is slower on low film-repellency surfaces due to a high dissipation at the edge of the receding film. This situation is reversed at high viscosity ratios, leading to a slower dewetting on high film-repellency surfaces due to the increased dissipation of the advancing surrounding phase.

Highlights

The spontaneous dewetting of a liquid film from a solid surface occurs in many important processes, such as printing and microscale patterning
In the field of micropatterning, which is of wide relevance to produce sensors for biotechnology and microsystems, thin polymer films are used to drive the spontaneous formation of droplet patterns upon dewetting[2]
In a liquid–liquid system, spontaneous dewetting occurs when the surface energy of a solid covered by a thin liquid film surrounded by an ambient liquid is reduced upon removal of the film

Summary

Introduction

The spontaneous dewetting of a liquid film from a solid surface occurs in many important processes, such as printing and microscale patterning. When the ratio of the viscosity of the outer liquid to the inner liquid is small, dewetting occurs faster on surfaces of increasing film repellency as previously reported[4].

Results

Conclusion