Evaporation-driven colloidal cluster assembly using droplets on superhydrophobic fractal-like structures

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Abstract

Microparticles can be considered building units for functional systems, but their assembly into larger structures typically involves complex methods. In this work, we show that a large variety of macro-agglomerate clusters (“supra-particles”) can be obtained, by systematically varying the initial particle concentration in an evaporating droplet, spanning more than 3 decades. The key is the use of robust superhydrophobic substrates: in this study we make use of a recently discovered kind of patterned surface with fractal-like microstructures which dramatically reduce the contact of the droplet with the solid substrate. Our results show a clear transition from quasi-2D to 3D clusters as a function of the initial particle concentration, and a clear transition from unstable to stable 3D spheroids as a function of the evaporation rate. The origin of such shape transitions can respectively be found in the dynamic wetting of the fractal-like structure, but also in the enhanced mechanical stability of the particle agglomerate as its particle packing fraction increases.
Original languageEnglish
Pages (from-to)506-515
Number of pages10
JournalSoft matter
Volume17
Issue number3
Early online date24 Nov 2020
DOIs
Publication statusPublished - 21 Jan 2021

Keywords

  • UT-Hybrid-D

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