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Lee J. Charge carriers created by interaction of a nonionic surfactant with water in a nonpolar medium. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.06.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Strubbe F, Neyts K. Charge transport by inverse micelles in non-polar media. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:453003. [PMID: 28895874 DOI: 10.1088/1361-648x/aa8bf6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Charged inverse micelles play an important role in the electrical charging and the electrodynamics of nonpolar colloidal dispersions relevant for applications such as electronic ink displays and liquid toner printing. This review examines the properties and the behavior of charged inverse micelles in microscale devices in the absence of colloidal particles. It is discussed how charge in nonpolar liquids is stabilized in inverse micelles and how conductivity depends on the inverse micelle size, water content and ionic impurities. Frequently used nonpolar surfactant systems are investigated with emphasis on aerosol-OT (AOT) and poly-isobutylene succinimide (PIBS) in dodecane. Charge generation in the bulk by disproportionation is studied from measurements of conductivity as a function of surfactant concentration and from generation currents in quasi steady-state. When a potential difference is applied, the steady-state situation can show electric field screening or complete charge separation. Different regimes of charge transport are identified when a voltage step is applied. It is shown how the transient and steady-state currents depend on the rate of bulk generation, on insulating layers and on the sticking or non-sticking behavior of charged inverse micelles at interfaces. For the cases of AOT and PIBS in dodecane, the magnitude of the generation rate and the type of interaction at the interface are very different.
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Affiliation(s)
- Filip Strubbe
- Electronics and Information Systems Department and Center for Nano and Biophotonics, Ghent University, Technologiepark Zwijnaarde 15, 9052 Zwijnaarde, Belgium
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Bakker HE, Besseling TH, Wijnhoven JEGJ, Helfferich PH, van Blaaderen A, Imhof A. Microelectrophoresis of Silica Rods Using Confocal Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:881-890. [PMID: 28045541 PMCID: PMC5348103 DOI: 10.1021/acs.langmuir.6b03863] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/31/2016] [Indexed: 06/06/2023]
Abstract
The electrophoretic mobility and the zeta potential (ζ) of fluorescently labeled colloidal silica rods, with an aspect ratio of 3.8 and 6.1, were determined with microelectrophoresis measurements using confocal microscopy. In the case where the colloidal particles all move at the same speed parallel to the direction of the electric field, we record a xyz-stack over the whole depth of the capillary. This method is faster and more robust compared to taking xyt-series at different depths inside the capillary to obtain the parabolic flow profile, as was done in previous work from our group. In some cases, rodlike particles do not move all at the same speed in the electric field, but exhibit a velocity that depends on the angle between the long axis of the rod and the electric field. We measured the orientation-dependent velocity of individual silica rods during electrophoresis as a function of κa, where κ-1 is the double layer thickness and a is the radius of the rod associated with the diameter. Thus, we determined the anisotropic electrophoretic mobility of the silica rods with different sized double layers. The size of the double layer was tuned by suspending silica rods in different solvents at different electrolyte concentrations. We compared these results with theoretical predictions. We show that even at already relatively high κa when the Smoluchowski limiting law is assumed to be valid (κa > 10), an orientation dependent velocity was measured. Furthermore, we observed that at decreasing values of κa the anisotropy in the electrophoretic mobility of the rods increases. However, in low polar solvents with κa < 1, this trend was reversed: the anisotropy in the electrophoretic mobility of the rods decreased. We argue that this decrease is due to end effects, which was already predicted theoretically. When end effects are not taken into account, this will lead to strong underestimation of the experimentally determined zeta potential.
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Lee J, Zhou ZL, Behrens SH. Charging Mechanism for Polymer Particles in Nonpolar Surfactant Solutions: Influence of Polymer Type and Surface Functionality. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:4827-4836. [PMID: 27135950 DOI: 10.1021/acs.langmuir.6b00583] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Surface charging phenomena in nonpolar dispersions are exploited in a wide range of industrial applications, but their mechanistic understanding lags far behind. We investigate the surface charging of a variety of polymer particles with different surface functionality in alkane solutions of a custom-synthesized and purified polyisobutylene succinimide (PIBS) polyamine surfactant and a related commercial surfactant mixture commonly used to control particle charge. We find that the observed electrophoretic particle mobility cannot be explained exclusively by donor-acceptor interactions between surface functional groups and surfactant polar moieties. Our results instead suggest an interplay of multiple charging pathways, which likely include the competitive adsorption of ions generated among inverse micelles in the solution bulk. We discuss possible factors affecting the competitive adsorption of micellar ions, such as the chemical nature of the particle bulk material and the size asymmetry between inverse micelles of opposite charge.
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Affiliation(s)
- Joohyung Lee
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive Northwest, Atlanta, Georgia 30332, United States
| | - Zhang-Lin Zhou
- HP Incorporated, 16399 West Bernardo Drive, San Diego, California 92127, United States
| | - Sven Holger Behrens
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive Northwest, Atlanta, Georgia 30332, United States
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Lee J, Zhou ZL, Alas G, Behrens SH. Mechanisms of Particle Charging by Surfactants in Nonpolar Dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:11989-11999. [PMID: 26484617 DOI: 10.1021/acs.langmuir.5b02875] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electric charging of colloidal particles in nonpolar solvents plays a crucial role for many industrial applications and products, including rubbers, engine oils, toners, or electronic displays. Although disfavored by the low solvent permittivity, particle charging can be induced by added surfactants, even nonionic ones, but the underlying mechanism is poorly understood, and neither the magnitude nor the sign of charge can generally be predicted from the particle and surfactant properties. The conclusiveness of scientific studies has been limited partly by a traditional focus on few surfactant types with many differences in their chemical structure and often poorly defined composition. Here we investigate the surface charging of poly(methyl methacrylate) particles dispersed in hexane-based solutions of three purified polyisobutylene succinimide polyamine surfactants with "subtle" structural variations. We precisely vary the surfactant chemistry by replacing only a single electronegative atom located at a fixed position within the polar headgroup. Electrophoresis reveals that these small differences between the surfactants lead to qualitatively different particle charging. In the respective particle-free surfactant solutions we also find potentially telling differences in the size of the surfactant aggregates (inverse micelles), the residual water content, and the electric solution conductivity as well as indications for a significant size difference between oppositely charged inverse micelles of the most hygroscopic surfactant. An analysis that accounts for the acid/base properties of all constituents suggests that the observed particle charging is better described by asymmetric adsorption of charged inverse micelles from the liquid bulk than by charge creation at the particle surface. Intramicellar acid-base interaction and intermicellar surfactant exchange help rationalize the formation of micellar ions pairs with size asymmetry.
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Affiliation(s)
- Joohyung Lee
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive NW, Atlanta, Georgia 30332, United States
| | - Zhang-Lin Zhou
- Hewlett-Packard Company, 16399 W Bernardo Drive, San Diego, California 92127, United States
| | - Guillermo Alas
- School of Chemistry and Biochemistry, Georgia Institute of Technology , 901 Atlantic Drive NW, Atlanta, Georgia 30332, United States
| | - Sven Holger Behrens
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive NW, Atlanta, Georgia 30332, United States
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Smith GN, Hallett JE, Eastoe J. Celebrating Soft Matter's 10th Anniversary: Influencing the charge of poly(methyl methacrylate) latexes in nonpolar solvents. SOFT MATTER 2015; 11:8029-8041. [PMID: 26369696 DOI: 10.1039/c5sm01190f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Sterically-stabilized poly(methyl methacrylate) (PMMA) latexes dispersed in nonpolar solvents are a classic, well-studied system in colloid science. This is because they can easily be synthesized with a narrow size distribution and because they interact essentially as hard spheres. These PMMA latexes can be charged using several methods (by adding surfactants, incorporating ionizable groups, or dispersing in autoionizable solvents), and due to the low relative permittivity of the solvents (εr ≈ 2 for alkanes to εr ≈ 8 for halogenated solvents), the charges have long-range interactions. The number of studies of these PMMA particles as charged species has increased over the past ten years, after few studies immediately following their discovery. A large number of variations in both the physical and chemical properties of the system (size, concentration, surfactant type, or solvent, as a few examples) have been studied by many groups. By considering the literature on these particles as a whole, it is possible to determine the variables that have an effect on the charge of particles. An understanding of the process of charge formation will add to understanding how to control charge in nonaqueous solvents as well as make it possible to develop improved technologically relevant applications for charged polymer nanoparticles.
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Affiliation(s)
- Gregory N Smith
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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van der Linden MN, Stiefelhagen JCP, Heessels-Gürboğa G, van der Hoeven JES, Elbers NA, Dijkstra M, van Blaaderen A. Charging of poly(methyl methacrylate) (PMMA) colloids in cyclohexyl bromide: locking, size dependence, and particle mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:65-75. [PMID: 25535669 DOI: 10.1021/la503665e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We studied suspensions of sterically stabilized poly(methyl methacrylate) (PMMA) particles in the solvent cyclohexyl bromide (CHB; εr = 7.92). We performed microelectrophoresis measurements on suspensions containing a single particle species and on binary mixtures, using confocal microscopy to measure the velocity profiles of the particles. We measured the charge of so-called locked PMMA particles, for which the steric stabilizer, a comb-graft stabilizer of poly(12-hydroxystearic acid) (PHSA) grafted on a backbone of PMMA, was covalently bonded to the particle, and for unlocked particles, for which the stabilizer was adsorbed to the surface of the particle. We observed that locked particles had a significantly higher charge than unlocked particles. We found that the charge increase upon locking was due to chemical coupling of 2-(dimethylamino)ethanol to the PMMA particles, which was used as a catalyst for the locking reaction. For particles of different size we obtained the surface potential and charge from the electrophoretic mobility of the particles. For locked particles we found that the relatively high surface potential (∼ +5.1 kBT/e or +130 mV) was roughly constant for all particle diameters we investigated (1.2 μm < σ < 4.4 μm), and that the particle charge was proportional to the square of the diameter.
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Affiliation(s)
- Marjolein N van der Linden
- Soft Condensed Matter, Debye Institute for Nanomaterials Science , Princetonplein 5, 3584 CC, Utrecht, The Netherlands
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Surfactant mediated charging of polymer particles in a nonpolar liquid. J Colloid Interface Sci 2013; 392:83-89. [DOI: 10.1016/j.jcis.2012.09.070] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 09/26/2012] [Indexed: 11/22/2022]
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Smith GN, Eastoe J. Controlling colloid charge in nonpolar liquids with surfactants. Phys Chem Chem Phys 2013. [DOI: 10.1039/c2cp42625k] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Li L, Zhang J, Sun H, Xu J, Sun D. Dispersion stability of organoclay in octane improved by adding nonionic surfactants. Colloids Surf A Physicochem Eng Asp 2012. [DOI: 10.1016/j.colsurfa.2012.09.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Poovarodom S, Poovarodom S, Berg JC. Effect of alkyl functionalization on charging of colloidal silica in apolar media. J Colloid Interface Sci 2010; 351:415-20. [DOI: 10.1016/j.jcis.2010.07.058] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/19/2010] [Accepted: 07/25/2010] [Indexed: 11/24/2022]
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Poovarodom S, Berg JC. Effect of particle and surfactant acid–base properties on charging of colloids in apolar media. J Colloid Interface Sci 2010; 346:370-7. [DOI: 10.1016/j.jcis.2010.03.012] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 02/27/2010] [Accepted: 03/07/2010] [Indexed: 11/26/2022]
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Patel MN, Smith PG, Kim J, Milner TE, Johnston KP. Electrophoretic mobility of concentrated carbon black dispersions in a low-permittivity solvent by optical coherence tomography. J Colloid Interface Sci 2010; 345:194-9. [DOI: 10.1016/j.jcis.2010.01.055] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/15/2010] [Accepted: 01/21/2010] [Indexed: 11/26/2022]
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Briscoe WH, Attard P. Counterion-only electrical double layer: A constrained entropy approach. J Chem Phys 2002. [DOI: 10.1063/1.1500359] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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