Polarity-Induced Reactive Wetting : Spreading and Retracting Sessile Water Drops
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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2024-06-14
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en
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Langmuir, Volume 40, issue 26, pp. 13562–13572
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.Description
Publisher Copyright: © 2024 The Authors. Published by American Chemical Society. | openaire: EC/HE/101062409/EU//SuperElectro
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Wong, W S Y, Kiseleva, M S & Naga, A 2024, ' Polarity-Induced Reactive Wetting : Spreading and Retracting Sessile Water Drops ', Langmuir, vol. 40, no. 26, pp. 13562–13572 . https://doi.org/10.1021/acs.langmuir.4c01085