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Evaporative Crystallization of Spirals

McBride, Samantha A and Dash, Susmita and Khan, Sami and Varanasi, Kripa K (2019) Evaporative Crystallization of Spirals. In: LANGMUIR, 35 (32). pp. 10484-10490.

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Official URL: https://dx.doi.org/10.1021/acs.langmuir.9b01002

Abstract

Spiral motifs are pervasive in nature, art, and technology due to their functional property of providing compact length. Nature is particularly adept at spiral patterning, and yet, the spirals observed in seashells, hurricanes, rams' horns, flower petals, etc. all evolve via disparate physical mechanisms. Here, we present a mechanism for the self-guided formation of spirals from evaporating saline drops via a coupling of crystallization and contact line dynamics. These patterns are in contrast to commonly observed patterns from evaporation of colloidal drops, which are discrete (rings, concentric rings) or continuous (clumps, uniform deposits) depending on the particle shape, contact line dynamics, and evaporation rate. Unlike the typical process of drop evaporation where the contact line moves radially inward, here, a thin film pinned by a ring of crystals ruptures radially outward. This motion is accompanied by a nonuniform pinning of the contact line due to crystallization, which generates a continuous propagation of pinning and depinning events to form a spiral. By comparing the relevant timescales of evaporation and diffusion, we show that a single dimensionless number can predict the occurrence of these patterns. These insights on self-guided crystallization of spirals could be used to create compact length templates.

Item Type: Journal Article
Additional Information: copyright for this article belongs to AMER CHEMICAL SOC
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Depositing User: Id for Latest eprints
Date Deposited: 18 Sep 2019 10:11
Last Modified: 18 Sep 2019 10:11
URI: http://eprints.iisc.ac.in/id/eprint/63516

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