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Qu Y, Li D, Liu J, Du F, Tan X, Zhou Y, Liu S, Xu W. Magnolia denudata leaf-derived near-infrared carbon dots as fluorescent nanoprobes for palladium(Ⅱ) detection and cell imaging. Microchem J 2022. [DOI: 10.1016/j.microc.2022.107375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Straub BB, Schmidt H, Rostami P, Henrich F, Rossi M, Kähler CJ, Butt HJ, Auernhammer GK. Flow profiles near receding three-phase contact lines: influence of surfactants. SOFT MATTER 2021; 17:10090-10100. [PMID: 34714897 PMCID: PMC8597584 DOI: 10.1039/d1sm01145f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
The dynamics of wetting and dewetting is largely determined by the velocity field near the contact lines. For water drops it has been observed that adding surfactant decreases the dynamic receding contact angle even at a concentration much lower than the critical micelle concentration (CMC). To better understand why surfactants have such a drastic effect on drop dynamics, we constructed a dedicated setup on an inverted microscope, in which an aqueous drop is held stationary while the transparent substrate is moved horizontally. Using astigmatism particle tracking velocimetry, we track the 3D displacement of the tracer particles in the flow. We study how surfactants alter the flow dynamics near the receding contact line of a moving drop for capillary numbers in the order of 10-6. Even for surfactant concentrations c far below the critical micelle concentration (c ≪ CMC) Marangoni stresses change the flow drastically. We discuss our results first in a 2D model that considers advective and diffusive surfactant transport and deduce estimates of the magnitude and scaling of the Marangoni stress from this. Modeling and experiment agree that a tiny gradient in surface tension of a few μN m-1 is enough to alter the flow profile significantly. The variation of the Marangoni stress with the distance from the contact line suggests that the 2D advection-diffusion model has to be extended to a full 3D model. The effect is ubiquitous, since surfactant is present in many technical and natural dewetting processes either deliberately or as contamination.
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Affiliation(s)
- Benedikt B Straub
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Henrik Schmidt
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Peyman Rostami
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
- Leibniz-Institut für Polymerforschung, Hohe Straße 6, D-01069 Dresden, Germany.
| | - Franziska Henrich
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Massimiliano Rossi
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
- Institute of Fluid Mechanics and Aerodynamics, Bundeswehr University Munich, D-85577 Neubiberg, Germany
| | - Christian J Kähler
- Institute of Fluid Mechanics and Aerodynamics, Bundeswehr University Munich, D-85577 Neubiberg, Germany
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Günter K Auernhammer
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
- Leibniz-Institut für Polymerforschung, Hohe Straße 6, D-01069 Dresden, Germany.
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Streck L, da Cruz PI, Fonseca JLC. Surface excess at water/air interface and micellization in solutions of an amphiphilic triblock copolymer. J DISPER SCI TECHNOL 2019. [DOI: 10.1080/01932691.2019.1650759] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- L. Streck
- Instituto de Química, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | - P. I. da Cruz
- Instituto de Química, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | - J. L. C. Fonseca
- Instituto de Química, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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Silva PS, Morelli S, Dragosavac MM, Starov VM, Holdich RG. Water in oil emulsions from hydrophobized metal membranes and characterization of dynamic interfacial tension in membrane emulsification. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.06.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Membrane emulsification: Formation of water in oil emulsions using a hydrophilic membrane. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.04.077] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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