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Polarity-Induced Reactive Wetting: Spreading and Retracting Sessile Water Drops.

Wong, William S Y; Kiseleva, Mariia S; Naga, Abhinav

Polarity-Induced Reactive Wetting: Spreading and Retracting Sessile Water Drops. Thumbnail


Authors

William S Y Wong

Mariia S Kiseleva



Abstract

Wetting is typically defined by the relative liquid to solid surface tension/energy, which are composed of polar and nonpolar subcontributions. Current studies often assume that they remain invariant, that is, surfaces are wetting-inert. Complex wetting scenarios, such as adaptive or reactive wetting processes, may involve time-dependent variations in interfacial energies. To maximize differences in energetic states, we employ low-energy perfluoroalkyls integrated with high-energy silica-based polar moieties grown on low-energy polydimethylsiloxane. To this end, we tune the hydrophilic-like wettability on these perfluoroalkyl-silica-polydimethylsiloxane surfaces. Drop contact behaviors range from invariantly hydrophobic at ca. 110° to rapidly spreading at ca. 0° within 5 s. Unintuitively, these vapor-grown surfaces transit toward greater hydrophilicity with increasing perfluoroalkyl deposition. Notably, this occurs as sequential silica-and-perfluoroalkyl deposition also leaves behind embedded polar moieties. We highlight how surfaces having such chemical heterogeneity are inherently wetting-reactive. By creating an abrupt wetting transition composed of reactive and inert domains, we introduce spatial dependency. Drops contacting the transition spread before retracting, occurring over the time scale of a few seconds. This phenomenon contradicts current understanding, exhibiting a uniquely (1) decreasing advancing contact angle and (2) increasing receding contact angle. To explain the behavior, we model such time- and space- dependent reactive wetting using first order kinetics. In doing so, we explore how reactive and recovery mechanisms govern the characteristic time scales of spreading and retracting sessile drops.

Citation

Wong, W. S. Y., Kiseleva, M. S., & Naga, A. (2024). Polarity-Induced Reactive Wetting: Spreading and Retracting Sessile Water Drops. Langmuir, 40(26), 13331-13752. https://doi.org/10.1021/acs.langmuir.4c01085

Journal Article Type Article
Acceptance Date May 23, 2024
Online Publication Date Jun 14, 2024
Publication Date Jun 14, 2024
Deposit Date Jul 10, 2024
Publicly Available Date Jul 10, 2024
Journal Langmuir
Print ISSN 0743-7463
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 40
Issue 26
Pages 13331-13752
DOI https://doi.org/10.1021/acs.langmuir.4c01085
Public URL https://durham-repository.worktribe.com/output/2512815

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