Surfactant-driven flow transitions in evaporating droplets

A. Marin*, R. Liepelt, M. Rossi, C.J. Kähler

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

66 Citations (Scopus)

Abstract

An evaporating droplet is a dynamic system in which flow is spontaneously generated to minimize the surface energy, dragging particles to the borders and ultimately resulting in the so-called “coffee-stain effect”. The situation becomes more complex at the droplet's surface, where surface tension gradients of different natures can compete with each other yielding different scenarios. With careful experiments and with the aid of 3D particle tracking techniques, we are able to show that different types of surfactants turn the droplet's surface either rigid or elastic, which alters the evaporating fluid flow, either enhancing the classical coffee-stain effect or leading to a total flow inversion. Our measurements lead to unprecedented and detailed measurements of the surface tension difference along the evaporating droplet's surface with good temporal and spatial resolution.
Original languageEnglish
Pages (from-to)1593-1600
JournalSoft matter
Volume12
Issue number5
DOIs
Publication statusPublished - 2016
Externally publishedYes

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