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Patterns in Drying Drops Dictated by Curvature-Driven Particle Transport
Shivani Semwal, P. Logesh Kumar, ,
Published in American Chemical Society
2018
PMID: 30145905
Volume: 34
   
Issue: 38
Pages: 11473 - 11483
Abstract
Patterns generated by controlled evaporation of droplets containing colloids are dictated by internally generated flows. This advective particle transport is crucial to the efficacy of printing and coating processes and is also an elegant route to the self-assembly of particles. We propose a novel particle transport route, which involves adsorption of particles to the interface and subsequent curvature-driven migration of the particles along the interface. This interface-mediated transport can be exploited to control the distribution of particles in the dried patterns, which we experimentally elucidate by achieving gravity-induced drop shape changes. Our experiments demonstrate that the interplay between the bulk and the interfacial transport leads to strikingly different patterns: while dried aqueous sessile drops of colloidal dispersions produce well known "coffee-rings", dried pendant drops lead to "coffee-eyes". We support our experimental findings using scaling arguments. In previous studies, the effect of gravity-induced change in drop shape on the patterns formed in drying drops has been neglected. However, we show that the structure of the patterns formed by the colloidal particles after solvent evaporation is markedly different when the drops are deformed by gravity. © 2018 American Chemical Society.
About the journal
JournalData powered by TypesetLangmuir
PublisherData powered by TypesetAmerican Chemical Society
ISSN07437463
Open AccessNo
Concepts (13)
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    Evaporation
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    Particle separators
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    Self assembly
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    Sols
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    Colloidal dispersion
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    Colloidal particle
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    CONTROLLED EVAPORATION
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    DISTRIBUTION OF PARTICLES
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    INTERFACIAL TRANSPORT
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    PARTICLE TRANSPORT
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    SELF-ASSEMBLY OF PARTICLES
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    Solvent evaporation
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    Drops