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Hacmon S, Liber SR, Shool L, Butenko AV, Atkins A, Sloutskin E. "Magic Numbers" in Self-Faceting of Alcohol-Doped Emulsion Droplets. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2301637. [PMID: 37259270 DOI: 10.1002/smll.202301637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/20/2023] [Indexed: 06/02/2023]
Abstract
Oil-in-water emulsion droplets spontaneously adopt, below some temperature Td , counterintuitive faceted and complex non-spherical shapes while remaining liquid. This transition is driven by a crystalline monolayer formed at the droplets' surface. Here, we show that ppm-level doping of the droplet's bulk by long-chain alcohols allows tuning Td by >50 °C, implying formation of drastically different interfacial structures. Furthermore, "magic" alcohol chain lengths maximize Td . This we show to arise from self-assembly of mixed alcohol:alkane interfacial structures of stacked alkane layers, co-crystallized with hydrogen-bonded alcohol dimers. These structures are accounted for theoretically and resolved by direct cryogenic transmission electron microscopy (cryoTEM), confirming the proposed structures. The discovered tunability of key properties of commonly-used emulsions by minute concentrations of specific bulk additives should benefit these emulsions' technological applicability.
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Affiliation(s)
- Sagi Hacmon
- Physics Department, Bar-Ilan University, Ramat Gan, 529002, Israel
- Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat Gan, 529002, Israel
| | - Shir R Liber
- Physics Department, Bar-Ilan University, Ramat Gan, 529002, Israel
- Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat Gan, 529002, Israel
| | - Lee Shool
- Physics Department, Bar-Ilan University, Ramat Gan, 529002, Israel
- Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat Gan, 529002, Israel
| | - Alexander V Butenko
- Physics Department, Bar-Ilan University, Ramat Gan, 529002, Israel
- Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat Gan, 529002, Israel
| | - Ayelet Atkins
- Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat Gan, 529002, Israel
| | - Eli Sloutskin
- Physics Department, Bar-Ilan University, Ramat Gan, 529002, Israel
- Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat Gan, 529002, Israel
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Nanikashvili PM, Butenko AV, Deutsch M, Lee D, Sloutskin E. Salt-induced stability and modified interfacial energetics in self-faceting emulsion droplets. J Colloid Interface Sci 2022; 621:131-138. [PMID: 35487043 DOI: 10.1016/j.jcis.2022.03.146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 10/18/2022]
Abstract
HYPOTHESIS The counterintuitive temperature-controlled self-faceting of water-suspended, surfactant-stabilized, liquid oil droplets provides new opportunities in engineering of smart liquids, the properties of which are controllable by external stimuli. However, many emulsions exhibiting self-faceting phenomena have limited stability due to surfactant precipitation. The emulsions' stability may be enhanced, and their inter-droplet electrostatic repulsion tuned, through controlled charge screening driven by varying-concentration added salts. Moreover, in many technologically-relevant situations, salts may already exist in the emulsion's aqueous phase. Yet, salts' impact on self-faceting effects has never been explored. We hypothesize that the self-faceting transitions' temperatures, and stability against surfactant precipitation, of ionic-surfactants-stabilized emulsions are significantly modified by salt introduction. EXPERIMENTS We explore the temperature-dependent impact of NaCl and CsCl salt concentration on the emulsions' phase diagrams, employing optical microscopy of emulsion droplet shapes and interfacial tension measurements, both sensitive to interfacial phase transitions. FINDINGS A salt concentration dependent increase in the self-faceting transition temperatures is found, and its mechanism elucidated. Our findings allow for a significant enhancement of the emulsions' stability, and provide the physical understanding necessary for future progress in research and applications of self-faceting phenomena in salt-containing emulsions.
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Affiliation(s)
- Pilkhaz M Nanikashvili
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Alexander V Butenko
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Moshe Deutsch
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Daeyeon Lee
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eli Sloutskin
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel; Bar-Ilan Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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Shool L, Butenko AV, Liber SR, Rabin Y, Sloutskin E. Anomalous Temperature-Controlled Concave-Convex Switching of Curved Oil-Water Menisci. J Phys Chem Lett 2021; 12:6834-6839. [PMID: 34279944 DOI: 10.1021/acs.jpclett.1c01937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
While the curvature of the classical liquid surfaces exhibits only a weak temperature dependence, we demonstrate here a reversible temperature-tunable concave-convex shape switching in capillary-contained, surfactant-decorated, oil-water interfaces. The observed switching gives rise to a concave-convex shape transition, which takes place as a function of the width of the containing capillary. This apparent violation of Young's equation results from a hitherto-unreported sharp reversible hydrophobic-hydrophilic transition of the glass capillary walls. The transition is driven by the interfacial freezing effect, which controls the balance between the competing surfactants' adsorption on, and consequent hydrophobization of, the capillary walls and their incorporation into the interfacially frozen monolayer. Since capillary wetting by surfactant solutions is fundamental for a wide range of technologies and natural phenomena, the present observations have important implications in many fields, from fluid engineering to biology, and beyond.
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Affiliation(s)
- Lee Shool
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Alexander V Butenko
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Shir R Liber
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yitzhak Rabin
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Eli Sloutskin
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
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Polyhedral liquid droplets: Recent advances in elucidation and application. Curr Opin Colloid Interface Sci 2020. [DOI: 10.1016/j.cocis.2020.05.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abubakar AA, Yilbas BS, Al-Qahtani H, Hassan G. Carbonated Water Droplet Can Ease Dust Mitigation from Hydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:10504-10518. [PMID: 32787027 DOI: 10.1021/acs.langmuir.0c01702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Carbonated water droplets can ease the difficulties faced by distilled water droplets mitigating dust particles from hydrophobic surfaces. Rising of CO2 bubbles in carbonated water droplets and their interaction with the flow structure, created by Marangoni and buoyancy possessions, in droplets are investigated. Spreading and infusion (cloaking) of carbonated water on dust surfaces are analyzed, and the rate at which bubbles formed inside the carbonated water droplet, as placed on a dusty hydrophobic surface, is examined. Flow structures formed inside the carbonated water droplet are simulated, and findings are compared to those corresponding to the distilled water droplet. Dust mitigation from the hydrophobic surface toward droplet liquid inside is evaluated using the high-speed recording system, and the results are compared with those of predictions. It is found that carbonated water spreads and infuses onto dust particles at a higher rate than that at which distilled water does. The rising bubble generates wake-like flow in the fluid while modifying the flow structure inside the droplet; hence, the number of circulating structures increases from two to four in droplet fluid. The dust particles picked up by flow currents are redistributed over the entire carbonated water droplet, while mitigated dust particles remain in the lower region of the distilled water droplet. Bubbles formed inside the carbonated water droplet improve dust lifting and rate of dust mitigation from the surface.
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Affiliation(s)
- Abba A Abubakar
- Mechanical Engineering Department, KFUPM, Dhahran 31261, Saudi Arabia
| | - Bekir S Yilbas
- Mechanical Engineering Department, KFUPM, Dhahran 31261, Saudi Arabia
| | | | - Ghassan Hassan
- Mechanical Engineering Department, KFUPM, Dhahran 31261, Saudi Arabia
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Liber SR, Marin O, Butenko AV, Ron R, Shool L, Salomon A, Deutsch M, Sloutskin E. Polyhedral Water Droplets: Shape Transitions and Mechanism. J Am Chem Soc 2020; 142:8672-8678. [DOI: 10.1021/jacs.0c00184] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Shir R. Liber
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Orlando Marin
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Alexander V. Butenko
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Racheli Ron
- Chemistry Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Lee Shool
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Adi Salomon
- Chemistry Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Moshe Deutsch
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Eli Sloutskin
- Physics Department & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
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Cholakova D, Valkova Z, Tcholakova S, Denkov N, Binks BP. Spontaneous particle desorption and "Gorgon" drop formation from particle-armored oil drops upon cooling. SOFT MATTER 2020; 16:2480-2496. [PMID: 32068204 DOI: 10.1039/c9sm02354b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study how the phenomenon of drop "self-shaping" (Denkov et al., Nature, 528, 2015, 392), in which oily emulsion drops undergo a spontaneous series of shape transformations upon emulsion cooling, is affected by the presence of adsorbed solid particles, like those used in Pickering emulsion stabilization. Experiments with several types of latex particles, and with added surfactant of low concentration to enable drop self-shaping, revealed several new unexpected phenomena: (1) adsorbed latex particles rearranged into regular hexagonal lattices upon freezing of the surfactant adsorption layer. (2) Spontaneous particle desorption from the drop surface was observed at a certain temperature - a remarkable phenomenon, as the solid particles are known to irreversibly adsorb on fluid interfaces. (3) Very strongly adhered particles to drop surfaces acted as a template to enable the formation of tens to hundreds of semi-liquid fibres, growing outwards from the drop surface, thus creating a shape resembling the Gorgon head from Greek mythology. Mechanistic explanations of all observed phenomena are provided using our understanding of the rotator phase formation on the surface of the cooled drops. The surface rotator phase creates positive line tension at the contact line formed between the particle surface and the fluid interface, which causes the particle ejection from the drop surface.
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Affiliation(s)
- Diana Cholakova
- Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, 1 James Bourchier Avenue, 1164 Sofia, Bulgaria.
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