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Wang Z, Miksis MJ, Vlahovska PM. Electrostatic force on a spherical particle confined between two planar surfaces. SOFT MATTER 2023; 19:7663-7672. [PMID: 37782279 DOI: 10.1039/d3sm00934c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
A charge-free particle in a uniform electric field experiences no net force in an unbounded domain. A boundary, however, breaks the symmetry and the particle can be attracted or repelled to it, depending on the applied field direction [Z. Wang et al., Phys. Rev. E, 2022, 106, 034607]. Here, we investigate the effect of a second boundary because of its common occurrence in practical applications. We consider a spherical particle suspended between two parallel walls and subjected to a uniform electric field, applied in a direction either normal or tangential to the surfaces. All media are modeled as leaky dielectrics, thus allowing for the accumulation of free charge at interfaces, while bulk media remain charge-free. The Laplace equation for the electric potential is solved using a multipole expansion and the boundaries are accounted for by a set of images. The results show that in the case of a normal electric field, which corresponds to a particle between two electrodes, the force is always attractive to the nearer boundary and, in general, weaker that the case of only one wall. Intriguingly, for a given particle-wall separation we find that the force may vary nonmonotonically with confinement and its magnitude may exceed the one-wall value. In the case of tangential electric field, which corresponds to a particle between insulating boundaries, the force follows the same trends but it is always repulsive.
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Affiliation(s)
- Zhanwen Wang
- Theoretical and Applied Mechanics Program, Northwestern University, Evanston, IL 60208, USA
| | - Michael J Miksis
- Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA.
| | - Petia M Vlahovska
- Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA.
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Hybrid Nanoparticles at Fluid-Fluid Interfaces: Insight from Theory and Simulation. Int J Mol Sci 2023; 24:ijms24054564. [PMID: 36901995 PMCID: PMC10003740 DOI: 10.3390/ijms24054564] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023] Open
Abstract
Hybrid nanoparticles that combine special properties of their different parts have numerous applications in electronics, optics, catalysis, medicine, and many others. Of the currently produced particles, Janus particles and ligand-tethered (hairy) particles are of particular interest both from a practical and purely cognitive point of view. Understanding their behavior at fluid interfaces is important to many fields because particle-laden interfaces are ubiquitous in nature and industry. We provide a review of the literature, focusing on theoretical studies of hybrid particles at fluid-fluid interfaces. Our goal is to give a link between simple phenomenological models and advanced molecular simulations. We analyze the adsorption of individual Janus particles and hairy particles at the interfaces. Then, their interfacial assembly is also discussed. The simple equations for the attachment energy of various Janus particles are presented. We discuss how such parameters as the particle size, the particle shape, the relative sizes of different patches, and the amphiphilicity affect particle adsorption. This is essential for taking advantage of the particle capacity to stabilize interfaces. Representative examples of molecular simulations were presented. We show that the simple models surprisingly well reproduce experimental and simulation data. In the case of hairy particles, we concentrate on the effects of reconfiguration of the polymer brushes at the interface. This review is expected to provide a general perspective on the subject and may be helpful to many researchers and technologists working with particle-laden layers.
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3
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Su Y, Lu C, Chang C, Li J, Sun Y, Zhang W, Gong L, Gu L, Yang Y. Preparation and characterization of W 1 /O/W 2 emulsions stabilized by glycated and heat-modified egg white proteins. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2022; 102:5795-5807. [PMID: 35411595 DOI: 10.1002/jsfa.11929] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/03/2022] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Water-in-oil-in-water (W1 /O/W2 ) emulsions stabilized by protein-carbohydrate complexes were prepared from an inner water phase (W1 ), an oil phase (O) and an outer water phase (W2 ). The complexes consisted of heat-induced aggregates (HIAs) of isomalto-oligosaccharide/egg white protein Maillard conjugates. The effects of polyglycerol ester of polyricinoleic acid (PGPR) concentration, HIA concentration, W1 -to-O volume ratio and W1 /O-to-W2 volume ratio on the properties of the W1 /O/W2 emulsions were systematically investigated. RESULTS At sufficiently high PGPR concentrations (>2%), the emulsions possess a high negative charge (≈-44 mV). The encapsulation efficiency of the emulsions, which was determined by incorporating a hydrophilic yellow dye in the inner water phase prior to homogenization, was relatively high (up to 93%) and did not change significantly during 14-day storage at 4 °C. All emulsions were fluids that exhibited shear thinning behavior. CONCLUSION Overall, this study shows that nature-derived emulsifiers can be used to create W1 /O/W2 emulsions suitable for application in the food industry. In addition, we provided a viable strategy to encapsulate water-soluble nutrients. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Yujie Su
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Cheng Lu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Cuihua Chang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Junhua Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Yujia Sun
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Wanqiu Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Lin Gong
- Hunan Engineering and Technology Research Center for Food Flavors and Flavorings, Jinshi, China
| | - Luping Gu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Yanjun Yang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China
- School of Food Science and Technology, Jiangnan University, Wuxi, China
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4
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Wang Z, Miksis MJ, Vlahovska PM. Particle-surface interactions in a uniform electric field. Phys Rev E 2022; 106:034607. [PMID: 36266874 DOI: 10.1103/physreve.106.034607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 08/23/2022] [Indexed: 06/16/2023]
Abstract
The electrostatic force on a spherical particle near a planar surface is calculated for the cases of a uniform electric field applied in either normal or tangential direction to the surface. The particle and suspending media are assumed to be weakly conducting, so that that the leaky dielectric model applies. The Laplace equation for the electric potential is solved in bipolar coordinate system and the potential is obtained in terms of a series expansion of Legendre polynomials. The force on the particle is calculated using the Maxwell tensor. We find that in the case of normal electric field, which corresponds to a particle near an electrode, the force is always attractive but at a given separation it varies nontrivially with particle-suspending medium conductivity ratio; the force on a particle that is more conducting than the suspending medium is much larger compared to the force on a particle less conducing than the suspending medium. In the case of tangential electric field, which corresponds to a particle near an insulating boundary, the force is always repulsive.
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Affiliation(s)
- Zhanwen Wang
- Theoretical and Applied Mechanics Program, Northwestern University, Evanston, Illinois 60208, USA
| | - Michael J Miksis
- Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, USA
| | - Petia M Vlahovska
- Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, USA
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Heidari F, Jafari SM, Ziaiifar AM, Anton N. Preparation of Pickering Emulsions Stabilized by Modified Silica Nanoparticles via the Taguchi Approach. Pharmaceutics 2022; 14:pharmaceutics14081561. [PMID: 36015190 PMCID: PMC9415153 DOI: 10.3390/pharmaceutics14081561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/05/2022] [Accepted: 07/24/2022] [Indexed: 02/01/2023] Open
Abstract
In this study, oil-in-water Pickering emulsions (PEs) were prepared by modified silica nanoparticles (MSNs) with cetyltrimethylammonium bromide (CTAB) using the Taguchi approach. The surface modification of SiO2 nanoparticles (NPs) was performed in different conditions, temperatures, pH levels, and amounts of CTAB as a coating agent, followed by an evaluation of their physicochemical properties. After treatment of the SiO2 NPs, the relationship of the MSNs’ surface properties and their efficiency in stabilizing Pickering emulsions was investigated by considering the zeta potential (ZP) and emulsion physical stability as main responses, respectively. Results disclosed were then supported by additional characterization, such as thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), and scanning electron microscopy. Results demonstrated that temperature has the most important role in the treatment of SiO2 nanoparticles, and allows for the identification of the best experimental conditions, i.e., range of zeta potential of MSNs to produce more efficient NPs, as well as the best stabilization of PEs.
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Affiliation(s)
- Fatemeh Heidari
- Faculty of Food Science and Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 4913815739, Iran; (F.H.); (A.M.Z.)
| | - Seid Mahdi Jafari
- Faculty of Food Science and Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 4913815739, Iran; (F.H.); (A.M.Z.)
- Correspondence:
| | - Aman Mohammad Ziaiifar
- Faculty of Food Science and Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 4913815739, Iran; (F.H.); (A.M.Z.)
| | - Nicolas Anton
- INSERM (French National Institute of Health and Medical Research), UMR 1260, Regenerative Nanomedicine (RNM), FMTS, University of Strasbourg, F-67000 Strasbourg, France;
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Vialetto J, Zanini M, Isa L. Attachment and detachment of particles to and from fluid interfaces. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2021.101560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Keane RK, Hong W, He W, Teale S, Bancroft R, Dinsmore AD. Adsorption of Hydrophilic Silica Nanoparticles at Oil-Water Interfaces with Reversible Emulsion Stabilization by Ion Partitioning. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2821-2831. [PMID: 35188775 DOI: 10.1021/acs.langmuir.1c02919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Adsorption of particles at oil-water interfaces is the basis of Pickering emulsions, which are common in nature and industry. For hydrophilic anionic particles, electrostatic repulsion and the absence of wetting inhibit spontaneous adsorption and limit the scope of materials that can be used in emulsion-based applications. Here, we explore how adding ions that selectively partition in the two fluid phases changes the interfacial electric potential and drives particle adsorption. We add oil-soluble tetrabutyl ammonium perchlorate (TBAP) to the nonpolar phase and Ludox silica nanoparticles or silica microparticles to the aqueous phase. We find a well-defined threshold TBAP concentration, above which emulsions are stable for months. This threshold increases with the particle concentration and with the oil's dielectric constant. Adding NaClO4 salt to water increases the threshold and causes spontaneous particle desorption and droplet coalescence even without agitation. The results are explained by a model based on the Poisson-Boltzmann theory, which predicts that the perchlorate anions (ClO4-) migrate into the water phase and leave behind a net positive charge in the oil. Our results show how a large class of inorganic hydrophilic, anionic nanoparticles can be used to stabilize emulsions in a reversible and stimulus-responsive way, without surface modifications.
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Affiliation(s)
- Robert K Keane
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Wei Hong
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Wei He
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Sam Teale
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Robbie Bancroft
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Anthony D Dinsmore
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, United States
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8
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Zhao Y, Lu Y, Wang D. Tracking of Nanoparticle Diffusion at a Liquid-Liquid Interface Adsorbed by Nonionic Surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12118-12127. [PMID: 34610245 DOI: 10.1021/acs.langmuir.1c01978] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Emulsions stabilized by both nanoparticles and surfactants often display longer shelf life than those stabilized by nanoparticles or surfactants alone. Although numerous works have been conducted to understand the effect of nanoparticles and surfactants on the variation of interfacial tension, little is known about interfacial diffusion when both nanoparticles and surfactants are present at interfaces. In this work, we used single-particle fluorescence tracking to study the lateral diffusion of individual hydrophobic nanoparticles at hexane-glycerol interfaces adsorbed by different amounts of nonionic surfactants. When the surfactant concentration is over a threshold, we found that the nanoparticle diffusion exhibits a two-regime behavior involving short-time Brownian and the emergence of subdiffusive, non-Gaussian, and dynamically anticorrelated diffusion in the long lag time regime. A stepwise analysis rationalized diffusion in different lag time regimes, leading to a mechanistic interpretation regarding the two-regime behavior. These results could provide insight into the understanding of the synergistic effect for the surfactant-assistant Pickering emulsion.
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Affiliation(s)
- Yuehua Zhao
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
- University of Science and Technology of China, Hefei 230026, P. R. China
| | - Yuyuan Lu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Dapeng Wang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
- University of Science and Technology of China, Hefei 230026, P. R. China
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9
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Taheri A, Kashaninejad M, Tamaddon AM, Jafari SM. Comparison of binary cress seed mucilage (CSM)/β-lactoglobulin (BLG) and ternary CSG-BLG-Ca (calcium) complexes as emulsifiers: Interfacial behavior and freeze-thawing stability. Carbohydr Polym 2021; 266:118148. [PMID: 34044955 DOI: 10.1016/j.carbpol.2021.118148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/21/2021] [Accepted: 04/29/2021] [Indexed: 11/24/2022]
Abstract
Protein-polysaccharide complexes often exhibit amended techno-functional characteristics when compared to their individual participant biomolecules. In this study, a complex coacervation of cress seed mucilage (CSM)/β-lactoglobulin (Blg) was used for stabilizing oil-in-water emulsions; they were characterized in terms of physical properties, droplet-size distribution and microstructure. Also, a comprehensive study was carried out on interfacial rheological responses and on the corresponding emulsion stability of different complexes. Freeze-thaw stability of the produced emulsions which had from mixtures of CSM-Blg was also evaluated. More than the size of droplets, interfacial rheological characteristics were associated with the properties of the adsorbed layers and with the stability of emulsions in storage. Using the CSM-Blg-Ca ultimately resulted in emulsions that proved stable against creaming, with no sign of phase separation over 3 weeks. These results show protein-polysaccharide complexes as appropriate emulsifiers that can make emulsion-based products resistant to unwanted changes caused by freeze-thawing.
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Affiliation(s)
- Afsaneh Taheri
- Department of Food Process Engineering, Faculty of Food Science and Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
| | - Mahdi Kashaninejad
- Department of Food Process Engineering, Faculty of Food Science and Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
| | - Ali Mohammad Tamaddon
- Department of Pharmaceutical Nanotechnology and Center for Nanotechnology in Drug Delivery, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Seid Mahdi Jafari
- Department of Food Process Engineering, Faculty of Food Science and Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
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10
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Huang F, Liang Y, He Y. On the Pickering emulsions stabilized by calcium carbonate particles with various morphologies. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.123722] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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11
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Wang A, Zwanikken JW, Kaz DM, McGorty R, Goldfain AM, Rogers WB, Manoharan VN. Before the breach: Interactions between colloidal particles and liquid interfaces at nanoscale separations. Phys Rev E 2019; 100:042605. [PMID: 31771009 DOI: 10.1103/physreve.100.042605] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Indexed: 06/10/2023]
Abstract
Particles bound to fluid-fluid interfaces are widely used to study self-assembly and to make materials such as Pickering emulsions. In both contexts, the lateral interactions between such particles have been studied extensively. However, much less is known about the normal interactions between a particle and the interface prior to contact. We use digital holographic microscopy to measure the dynamics of individual micrometer-size colloidal particles as they approach an interface between an aqueous phase and oil. Our measurements show that the interaction between the particle and interface changes nonmonotonically as a function of salt concentration, from repulsive at 1 mM to attractive at tens of mM to negligible at 100 mM and attractive again above 200 mM. In the attractive regimes, the particles can bind to the interface at nanometer-scale separation without breaching it. Classical Derjaguin-Landau-Verwey-Overbeek theory does not explain these observations. However, a theory that accounts for nonlinear screening and correlations between the ions does predict the nonmonotonic dependence on salt concentration and produces trajectories that agree with experimental data. We further show that the normal interactions determine the lateral interactions between particles that are bound to the interface. Because the interactions we observe occur at salt concentrations used to make Pickering emulsions and other particle-laden interfaces, our results suggest that particle arrangements at the interface are likely out of equilibrium on experimental timescales.
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Affiliation(s)
- Anna Wang
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
- School of Chemistry, UNSW Sydney, New South Wales 2052, Australia
| | - Jos W Zwanikken
- Department of Physics, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA
| | - David M Kaz
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Ryan McGorty
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics and Biophysics, University of San Diego, San Diego, California 92110, USA
| | - Aaron M Goldfain
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - W Benjamin Rogers
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
- Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Vinothan N Manoharan
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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12
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Sofla SJD, James LA, Zhang Y. Understanding the behavior of H+-protected silica nanoparticles at the oil-water interface for enhanced oil recovery (EOR) applications. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.09.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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Facal Marina P, Xu J, Wu X, Xu H. Thinking outside the box: placing hydrophilic particles in an oil phase for the formation and stabilization of Pickering emulsions. Chem Sci 2018; 9:4821-4829. [PMID: 29910934 PMCID: PMC5982226 DOI: 10.1039/c8sc00678d] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/26/2018] [Indexed: 01/24/2023] Open
Abstract
Pickering emulsions, also known as particle stabilized emulsions, are one kind of extremely important emulsion for both fundamental research and practical applications. Many colloidal particles have been utilized as emulsifiers to stabilize Pickering emulsions. However, the most challenging issue is preparing Pickering emulsions with highly hydrophilic particles, because their adsorption onto oil-water interfaces is either thermodynamically or kinetically unfavorable. Although several strategies have been developed to overcome the poor ability of the hydrophilic particles to stabilize the emulsions, surface modification and functionalization of the hydrophilic particles or a change in solvent (i.e. water phase) conditions such as pH and ionic strength is required. Herein, we present an effective and not yet explored strategy to stabilize Pickering emulsions with unmodified highly hydrophilic particles, strikingly, without changing the solvent conditions. The innovative aspect of the strategy presented here is the unconventional dispersion of hydrophilic particles in an oil phase before emulsification, while the results experimentally demonstrate the theoretical calculations predicted more than a decade ago. This study will promote the diversity of Pickering emulsions and expand their real-world applications.
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Affiliation(s)
- Paula Facal Marina
- Future Industries Institute , University of South Australia , Mawson Lakes Campus , Adelaide , SA 5095 , Australia .
| | - Jie Xu
- Future Industries Institute , University of South Australia , Mawson Lakes Campus , Adelaide , SA 5095 , Australia .
| | - Xuan Wu
- Future Industries Institute , University of South Australia , Mawson Lakes Campus , Adelaide , SA 5095 , Australia .
| | - Haolan Xu
- Future Industries Institute , University of South Australia , Mawson Lakes Campus , Adelaide , SA 5095 , Australia .
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14
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Zhang J, Song Y, Li D. Electrokinetic motion of a spherical polystyrene particle at a liquid-fluid interface. J Colloid Interface Sci 2018; 509:432-439. [DOI: 10.1016/j.jcis.2017.09.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 08/31/2017] [Accepted: 09/02/2017] [Indexed: 11/28/2022]
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15
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Fabrication and characterization of Pickering emulsions and oil gels stabilized by highly charged zein/chitosan complex particles (ZCCPs). Food Chem 2016; 213:462-469. [DOI: 10.1016/j.foodchem.2016.06.119] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/01/2016] [Accepted: 06/30/2016] [Indexed: 01/07/2023]
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16
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Hu YQ, Yin SW, Zhu JH, Qi JR, Guo J, Wu LY, Tang CH, Yang XQ. Fabrication and characterization of novel Pickering emulsions and Pickering high internal emulsions stabilized by gliadin colloidal particles. Food Hydrocoll 2016. [DOI: 10.1016/j.foodhyd.2016.05.028] [Citation(s) in RCA: 179] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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17
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Ridel L, Bolzinger MA, Gilon-Delepine N, Dugas PY, Chevalier Y. Pickering emulsions stabilized by charged nanoparticles. SOFT MATTER 2016; 12:7564-76. [PMID: 27510805 DOI: 10.1039/c6sm01465h] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The stabilization of o/w Pickering emulsions in cases of weak adsorption of solid particles at the surface of oil droplets is addressed. Though the adsorption is usually very strong and irreversible when partial wetting conditions are fulfilled, electrostatic repulsions between charged solid particles act against the adsorption. The regime of weak adsorption was reached using charged silica nanoparticles at high pH and low ionic strength. O/w Pickering emulsions of the diisopropyl adipate oil were stabilized by colloidal nanoparticles of Ludox® AS40 consisting of non-aggregated particles of bare silica (hydrophilic). The combination of stability assessment, droplet size and electrokinetic potential measurements at various pH values, adsorption isotherms and cryo-SEM observations of the adsorbed layers disclosed the specificities of the stabilization of Pickering emulsions by adsorption of solid nanoparticles against strong electrostatic repulsions. Not only the long-term stability of emulsions was poor under strong electrostatic repulsions at high pH, but emulsification failed since full dispersion of oil could not be achieved. Emulsion stability was ensured by decreasing electrostatic repulsions by lowering the pH from 9 to 3. Stable emulsions were stabilized by a monolayer of silica particles at 54% coverage of the oil droplet surface at low silica content and an adsorption regime as multilayers was reached at higher concentrations of silica although there was no aggregation of silica in the bulk aqueous phase.
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Affiliation(s)
- Laure Ridel
- University of Lyon, Laboratoire d'Automatique et de Génie des Procédés, University of Lyon 1, CNRS UMR 5007, Villeurbanne, France.
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18
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Everts JC, Samin S, van Roij R. Tuning Colloid-Interface Interactions by Salt Partitioning. PHYSICAL REVIEW LETTERS 2016; 117:098002. [PMID: 27610887 DOI: 10.1103/physrevlett.117.098002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Indexed: 06/06/2023]
Abstract
We show that the interaction of an oil-dispersed colloidal particle with an oil-water interface is highly tunable from attractive to repulsive, either by varying the sign of the colloidal charge via charge regulation or by varying the difference in hydrophilicity between the dissolved cations and anions. In addition, we investigate the yet unexplored interplay between the self-regulated colloidal surface charge distribution with the planar double layer across the oil-water interface and the spherical one around the colloid. Our findings explain recent experiments and have direct relevance for tunable Pickering emulsions.
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Affiliation(s)
- J C Everts
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - S Samin
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - R van Roij
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
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19
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Boglaienko D, Tansel B. Gravity induced densification of floating crude oil by granular materials: Effect of particle size and surface morphology. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 556:146-153. [PMID: 26971215 DOI: 10.1016/j.scitotenv.2016.01.214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 01/29/2016] [Accepted: 01/30/2016] [Indexed: 06/05/2023]
Abstract
Densification and sedimentation of floating crude oil to the bottom of water column reduces the radius of a spill and its mobility, preventing direct contamination of beaches, coastal flora and fauna. Performances of different natural granular materials were evaluated for capturing efficiency of floating fresh South Louisiana crude oil. The granular materials studied were quartz sand with medium (20-30mesh) and fine (40-100mesh) particle size, limestone with coarse (4-10mesh) and medium (16-40mesh) particle size, beach sand (20-80mesh), and clay (kaolin with ferric oxide; passing 200mesh). Beach sand (mixture of quartz and limestone 20-80mesh) and limestone (16-40mesh) demonstrated better performance for capture, densification and submergence of the crude oil among the materials evaluated. The behavior of granular particles with the hydrophobic phase can be classified as (1) immersion entrapment inside the hydrophobic phase (slurry), and (2) partial encapsulation of the hydrophobic phase by a single layer of particles (raft). With crude oil, the particles were primarily entrapped within the hydrophobic phase. Study of the effect of particle size and morphology (i.e., porosity) of the granular materials on capture performance showed that average surface pore size did not have a significant effect on aggregation with oil, however, higher capture efficiency was observed with materials of higher surface porosity (beach sand and limestone). The experiments revealed that there is a critical particle size range (passing 10mesh) which resulted in more effective aggregation of the granular materials with crude oil.
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Affiliation(s)
- Daria Boglaienko
- Florida International University, Civil and Environmental Engineering Department, Miami, FL, USA.
| | - Berrin Tansel
- Florida International University, Civil and Environmental Engineering Department, Miami, FL, USA.
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Buchcic C, Tromp RH, Meinders MBJ, Cohen Stuart MA. Assembly of jammed colloidal shells onto micron-sized bubbles by ultrasound. SOFT MATTER 2015; 11:1326-1334. [PMID: 25571985 DOI: 10.1039/c4sm02492c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Stabilization of gas bubbles in water by applying solid particles is a promising technique to ensure long-term stability of the dispersion against coarsening. However, the production of large quantities of particle stabilized bubbles is challenging. The delivery of particles to the interface must occur rapidly compared to the typical time scale of coarsening during production. Furthermore, the production route must be able to overcome the energy barriers for interfacial adsorption of particles. Here we demonstrate that ultrasound can be applied to agitate a colloidal dispersion and supply sufficient energy to ensure particle adsorption onto the air-water interface. With this technique we are able to produce micron-sized bubbles, solely stabilized by particles. The interface of these bubbles is characterized by a colloidal shell, a monolayer of particles which adopt a hexagonal packing. The particles are anchored to the interface owing to partial wetting and experience lateral compression due to bubble shrinkage. The combination of both effects stops coarsening once the interface is jammed with particles. As a result, stable bubbles are formed. Individual particles can desorb from the interface upon surfactant addition, though. The latter fact confirms that the particle shell is not covalently linked due to thermal sintering, but is solely held together by capillary interaction. In summary, we show that our ultrasound approach allows for the straightforward creation of micron-sized particle stabilized bubbles with high stability towards coarsening.
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Affiliation(s)
- C Buchcic
- Top Institute Food and Nutrition, Wageningen, The Netherlands.
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Nallamilli T, Mani E, Basavaraj MG. A model for the prediction of droplet size in Pickering emulsions stabilized by oppositely charged particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9336-45. [PMID: 25054284 DOI: 10.1021/la501785y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Colloidal particles irreversibly adsorb at fluid-fluid interfaces stabilizing what are commonly called "Pickering" emulsions and foams. A simple geometrical model, the limited coalescence model, was earlier proposed to estimate droplet sizes in emulsions. This model assumes that all of the particles are effective in stabilization. The model predicts that the average emulsion drop size scales inversely with the total number of particles, confirmed qualitatively with experimental data on Pickering emulsions. In recent years, there has been an increasing interest in synthesizing emulsions with oppositely charged particles (OCPs). In our experimental study, we observed that the drop size varies nonmonotonically with the number ratio of oppositely charged colloids, even when a fixed total number concentration of colloids is used, showing a minimum. We develop a mathematical model to predict this dependence of drop size on number ratio in such a mixed particle system. The proposed model is based on the hypothesis that oppositely charged colloids form stable clusters due to the strong electrostatic attraction between them and that these clusters are the effective stabilizing agents. The proposed model is a two-parameter model, parameters being the ratio of effective charge of OCPs (denoted as k) and the size of the aggregate containing X particles formed due to aggregation of OCPs. Because the size of aggregates formed during emulsification is not directly measurable, we use suitable values of parameters k and X to best match the experimental observations. The model predictions are in qualitative agreement with experimentally observed nonmonotonic variation of droplet sizes. Using experiments and theory, we present a physical insight into the formation of OCP stabilized Pickering emulsions. Our model upgrades the existing Wiley's limited coalescence model as applied to emulsions containing a binary mixture of oppositely charged particles.
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Affiliation(s)
- Trivikram Nallamilli
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras , Chennai-600036, Tamilnadu, India
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22
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Danov KD, Kralchevsky PA. Forces acting on dielectric colloidal spheres at a water/nonpolar fluid interface in an external electric field. 2. Charged particles. J Colloid Interface Sci 2013; 405:269-77. [DOI: 10.1016/j.jcis.2013.05.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 05/02/2013] [Indexed: 11/15/2022]
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23
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Forces acting on dielectric colloidal spheres at a water/nonpolar-fluid interface in an external electric field. 1. Uncharged particles. J Colloid Interface Sci 2013; 405:278-90. [DOI: 10.1016/j.jcis.2013.05.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 05/03/2013] [Accepted: 05/07/2013] [Indexed: 11/23/2022]
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24
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Garbin V, Crocker JC, Stebe KJ. Nanoparticles at fluid interfaces: Exploiting capping ligands to control adsorption, stability and dynamics. J Colloid Interface Sci 2012; 387:1-11. [DOI: 10.1016/j.jcis.2012.07.047] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 06/29/2012] [Accepted: 07/14/2012] [Indexed: 11/26/2022]
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25
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Wang H, Singh V, Behrens SH. Image Charge Effects on the Formation of Pickering Emulsions. J Phys Chem Lett 2012; 3:2986-90. [PMID: 26292238 DOI: 10.1021/jz300909z] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Vigorous mixing of an aqueous particle dispersion with oil usually produces a particle-stabilized emulsion (a "Pickering emulsion"), the longevity of which depends on the particles' wetting properties. A known exception occurs when particles fail to adsorb to the oil-water interface created during mixing because of a strong repulsion between charges on the particle surface and similar charges on the oil-water interface; in this case, no Pickering emulsion is formed. Here, we present experimental evidence that the rarely considered electrostatic image force can cause a much bigger hindrance to particle adsorption and prevent the formation of Pickering emulsions even when the particle interaction with the interface charge is attractive. A simple theoretical estimate confirms the observed magnitude of this effect and points at an important limitation of Pickering emulsification, a technology with widespread industrial applications and increasing popularity in materials research and development.
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26
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Novel parallel plate condenser for single particle electrostatic force measurements in atomic force microscope. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2011.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Interaction between like-charged particles at a liquid interface: Electrostatic repulsion vs. electrocapillary attraction. J Colloid Interface Sci 2010; 345:505-14. [DOI: 10.1016/j.jcis.2010.02.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 02/08/2010] [Accepted: 02/09/2010] [Indexed: 11/20/2022]
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Affiliation(s)
- M. N. Tamashiro
- Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970, Campinas, São Paulo, Brazil
| | - M. A. Constantino
- Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970, Campinas, São Paulo, Brazil
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29
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Fortuna S, Colard CAL, Troisi A, Bon SAF. Packing patterns of silica nanoparticles on surfaces of armored polystyrene latex particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12399-12403. [PMID: 19438175 DOI: 10.1021/la9010289] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Fascinating packing patterns of identical spherical and discotic objects on curved surfaces occur readily in nature and science. Examples include C(60) fullerenes, (1, 2) 13-atom cuboctahedral metal clusters, (3) and S-layer proteins on outer cell membranes. (4) Numerous situations with surface-arranged objects of variable size also exist, such as the lenses on insect eyes, biomineralized shells on coccolithophorids, (5) and solid-stabilized emulsion droplets (6) and bubbles. (7) The influence of size variations on these packing patterns, however, is studied sparsely. Here we investigate the packing of nanosized silica particles on the surface of polystyrene latex particles fabricated by Pickering miniemulsion polymerization of submicrometer-sized armored monomer droplets. We are able to rationalize the experimental morphology and the nearest-neighbor distribution with the help of Monte Carlo simulations. We show that broadening of the nanoparticle size distribution has pronounced effects on the self-assembled equilibrium packing structures, with original 12-point dislocations or grain-boundary scars gradually fading out.
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Affiliation(s)
- Sara Fortuna
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
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Boneva MP, Danov KD, Christov NC, Kralchevsky PA. Attraction between particles at a liquid interface due to the interplay of gravity- and electric-field-induced interfacial deformations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9129-9139. [PMID: 19719220 DOI: 10.1021/la9006873] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In a previous study, we established that the attraction between electrically charged particles attached to a water/tetradecane interface is stronger than predicted on the basis of the gravity-induced lateral capillary force. Here, our goal is to explain this effect. The investigated particles are hydrophobized glass spheres of radii between 240 and 320 microm. Their weight is large enough to deform the liquid interface. The interfacial deformation is considerably greater for charged particles because of the electrodipping force that pushes the particles toward the water phase. By independent experiments with particles placed between two electrodes, we confirmed the presence of electric charges at the particle/tetradecane interface. The theoretical analysis shows that if the distribution of these surface charges is isotropic, the meniscus produced by the particle electric field decays too fast with distance and cannot explain the experimental observations. However, if the surface-charge distribution is anisotropic, it induces a saddle-shaped deformation in the liquid interface around each particle. This deformation, which is equivalent to a capillary quadrupole, decays relatively slow. Its interference with the gravity-induced isotropic meniscus around the other particle gives rise to a long-range attractive capillary force, F approximately 1/L3 (L=interparticle distance). The obtained agreement between the experimental and theoretical curves, and the reasonable values of the parameters determined from the fits, indicate that the observed stronger attraction in the investigated system can be really explained as a hybrid interaction between gravity-induced "capillary charges" and electric-field-induced "capillary quadrupoles".
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Affiliation(s)
- Mariana P Boneva
- Laboratory of Chemical Physics & Engineering, Faculty of Chemistry, Sofia University, 1164 Sofia, Bulgaria
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31
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Lin IH, Koenig GM, de Pablo JJ, Abbott NL. Ordering of Solid Microparticles at Liquid Crystal−Water Interfaces. J Phys Chem B 2008; 112:16552-8. [DOI: 10.1021/jp807286s] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I-Hsin Lin
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - Gary M. Koenig
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - Juan J. de Pablo
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - Nicholas L. Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706
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33
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Tsuji S, Kawaguchi H. Thermosensitive pickering emulsion stabilized by poly(N-isopropylacrylamide)-carrying particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:3300-3305. [PMID: 18324842 DOI: 10.1021/la701780g] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Poly(N-isopropylacrylamide) (PNIPAM)-carrying particles were characterized as thermosensitive Pickering emulsifiers. Emulsions were prepared from various oils, such as heptane, hexadecane, trichloroethylene, and toluene, with PNIPAM-carrying particles. PNIPAM-carrying particles preferentially formed oil-in-water (O/W)-type emulsions with a variety of oils. All the emulsions stabilized by PNIPAM-carrying particles were stable for more than 3 months as long as they were stored at room temperature. However, when the emulsions were heated from room temperature to 40 degrees C, at which point the PNIPAM layer caused a coil-to-globule transition, phase separation occurred. Thus, by using thermosensitive PNIPAM-carrying particles as emulsifiers, the stability of the Pickering emulsions could be controlled by a slight change in temperature.
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Affiliation(s)
- Sakiko Tsuji
- Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
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34
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Xu T, Jin M, Xie Z, Jiang Z, Kuang Q, Wu H, Huang R, Zheng L. Tensions at liquid interfaces: a general filter for the separation of micro-/nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:2281-3. [PMID: 18290686 DOI: 10.1021/la7038569] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In this letter, we put forward a new strategy for the separation of micro-/nanoparticles with different sizes and densities by using the tensions at liquid interfaces. The interactions between particles and a liquid-liquid interface have been analyzed. Furthermore, we applied our strategy to the separation of two size-distributed Cu2O particles by using the water and n-pentanol interface, which demonstrates the feasibility of the proposed separation method.
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Affiliation(s)
- Tao Xu
- State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China
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35
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Tcholakova S, Denkov ND, Lips A. Comparison of solid particles, globular proteins and surfactants as emulsifiers. Phys Chem Chem Phys 2008; 10:1608-27. [DOI: 10.1039/b715933c] [Citation(s) in RCA: 342] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Zwanikken J, van Roij R. Charged colloidal particles and small mobile ions near the oil-water interface: destruction of colloidal double layer and ionic charge separation. PHYSICAL REVIEW LETTERS 2007; 99:178301. [PMID: 17995376 DOI: 10.1103/physrevlett.99.178301] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Indexed: 05/25/2023]
Abstract
We study suspensions of hydrophobic charged colloids in a demixed oil-water solvent with salt by means of a modified Poisson-Boltzmann theory, taking into account image-charge effects and partitioning of the monovalent ions. We find that the ion's aversion for oil can deform the double layers of the oil-dispersed colloids, which qualitatively affects the colloidal density profiles. The same theory also predicts crystallization of colloid-free micron-sized water-in-oil droplets at water volume fractions as small as approximately 10(-3) in a narrow range of the oil-dielectric constant. These findings explain recent observations by M. E. Leunissen et al. [Proc. Natl. Acad. Sci. U.S.A. 104, 2585 (2007)10.1073/pnas.0610589104].
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Affiliation(s)
- Jos Zwanikken
- Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
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37
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Leunissen ME, van Blaaderen A, Hollingsworth AD, Sullivan MT, Chaikin PM. Electrostatics at the oil-water interface, stability, and order in emulsions and colloids. Proc Natl Acad Sci U S A 2007; 104:2585-90. [PMID: 17307876 PMCID: PMC1800788 DOI: 10.1073/pnas.0610589104] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Oil-water mixtures are ubiquitous in nature and are particularly important in biology and industry. Usually additives are used to prevent the liquid droplets from coalescing. Here, we show that stabilization can also be obtained from electrostatics, because of the well known remarkable properties of water. Preferential ion uptake leads to a tunable droplet charge and surprisingly stable, additive-free, water-in-oil emulsions that can crystallize. For particle-stabilized ("Pickering") emulsions we find that even extremely hydrophobic, nonwetting particles can be strongly bound to (like-charged) oil-water interfaces because of image charge effects. These basic insights are important for emulsion production, encapsulation, and (self-)assembly, as we demonstrate by fabricating a diversity of structures in bulk, on surfaces, and in confined geometries.
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Affiliation(s)
- Mirjam E. Leunissen
- *Soft Condensed Matter, Debye Institute, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands; and
- To whom correspondence may be addressed. E-mail: , , or
| | - Alfons van Blaaderen
- *Soft Condensed Matter, Debye Institute, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands; and
- To whom correspondence may be addressed. E-mail: , , or
| | - Andrew D. Hollingsworth
- Department of Chemical Engineering
- Princeton Institute for the Science and Technology of Materials, and
| | - Matthew T. Sullivan
- Princeton Institute for the Science and Technology of Materials, and
- Department of Physics, Princeton University, Princeton, NJ 08534
| | - Paul M. Chaikin
- Princeton Institute for the Science and Technology of Materials, and
- Department of Physics, Princeton University, Princeton, NJ 08534
- To whom correspondence may be addressed. E-mail: , , or
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Boneva MP, Christov NC, Danov KD, Kralchevsky PA. Effect of electric-field-induced capillary attraction on the motion of particles at an oil–water interface. Phys Chem Chem Phys 2007; 9:6371-84. [DOI: 10.1039/b709123k] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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39
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Leunissen ME, Zwanikken J, van Roij R, Chaikin PM, van Blaaderen A. Ion partitioning at the oil–water interface as a source of tunable electrostatic effects in emulsions with colloids. Phys Chem Chem Phys 2007; 9:6405-14. [DOI: 10.1039/b711300e] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Danov KD, Kralchevsky PA. Electric forces induced by a charged colloid particle attached to the water–nonpolar fluid interface. J Colloid Interface Sci 2006; 298:213-31. [PMID: 16413564 DOI: 10.1016/j.jcis.2005.12.037] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2005] [Revised: 11/21/2005] [Accepted: 12/17/2005] [Indexed: 11/17/2022]
Abstract
Here, we solve the problem about the electric field of a charged dielectric particle, which is adsorbed at the water-nonpolar fluid (oil, air) boundary. The solution of this problem is a necessary step for the theoretical prediction of the electrodipping force acting on such particle, as well as of the electrostatic repulsion and capillary attraction between two adsorbed particles. In accordance with the experimental observations, we consider the important case when the surface charges are located at the particle-nonpolar fluid boundary. To solve the electrostatic problem, the Mehler-Fock integral transform is applied. In the special case when the dielectric constants of the particle and the nonpolar fluid are equal, the solution is obtained in a closed analytical form. In the general case of different dielectric constants, the problem is reduced to the numerical solution of an integral equation, which is carried out by iterations. The long-range asymptotics of the solution indicates that two similar particles repel each other as dipoles, whose dipole moments are related to the particle radius, contact angle, dielectric constant and surface charge density. The investigated short-range asymptotics ensures accurate calculation of the electrodipping force. For a fast and convenient application of the obtained results, the derived physical dependencies are tabulated as functions of the contact angle and the dielectric constants.
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Affiliation(s)
- Krassimir D Danov
- Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia, 1164 Sofia, Bulgaria
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