Jiang, J, Jackson, F, Tangparitkul, S et al. (2 more authors) (2023) Discontinuous dewetting dynamics of highly viscous droplets on chemically heterogeneous substrates. Journal of Colloid and Interface Science, 629 (Part B). pp. 345-356. ISSN 0021-9797
Abstract
Hypothesis
Droplet spreading on heterogeneous (chemical/structural) surfaces has revealed local disturbances that affect the advancing contact line. With droplet dewetting being less studied, we hypothesize that a receding droplet can be perturbed by localized heterogeneity which leads to irregular and discontinuous dewetting of the substrate.
Experiments
The sessile drop method was used to study droplet dewetting at a wettability boundary. One-half of a hydrophilic surface was hydrophobically modified with either i) methyloctyldichlorosilane or ii) clustered macromolecules. A Lattice Boltzmann method (LBM) simulation was also developed to determine the effect of contact angle hysteresis and boundary conditions on the droplet dynamics.
Findings
The two surface treatments were optimized to produce comparable water wetting characteristics. With a negative Gibbs free energy on the hydrophilic-half, the oil droplet receded to the hydrophobic-half. On the silanized surface, the droplet was pinned and the resultant droplet shape was a distorted spherical cap, having receded uniformly on the unmodified surface. Modifying the surface with clustered macromolecules, the droplet receded slightly to form a spherical cap. However, droplet recession was non-uniform and daughter droplets formed near the wettability boundary. The LBM simulation revealed that daughter droplets formed when > 164°, with the final droplet shape accurately described by imposing a diffuse wettability boundary condition.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022 Elsevier Inc. All rights reserved. This is an author produced version of an article, published in Journal of Colloid and Interface Science. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Wettability boundary; Heterogeneous surfaces; Droplet dewetting; Daughter droplet generation; Highly viscous oil; Lattice Boltzmann method |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mechanical Engineering (Leeds) > Institute of Engineering Thermofluids, Surfaces & Interfaces (iETSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Nov 2022 16:12 |
Last Modified: | 15 Sep 2023 00:13 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.jcis.2022.09.064 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:193414 |