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Charging and discharging of single colloidal particles at oil/water interfaces.

Gao P, Xing X, Li Y, Ngai T, Jin F - Sci Rep (2014)

Bottom Line: The charging process is highly dependent on the sliding distances, and gives rise to long-ranged repulsions that protect interfacial particles from coagulating at the interface by the presence of electrolyte.These triboelectric charges, however, are compensated within several hours, which affect the stability of interfacial particles.Importantly, by charging different kinds of colloidal particles using various spreading solvents and dispersion methods, we have demonstrated that charging and discharging of single colloidal particles at oil/water interfaces impacts a broad range of dynamical behavior.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, P. R. China 230026 [2].

ABSTRACT
The physical behavior of solid colloids trapped at a fluid-fluid interface remains in itself an open fundamental issue. Here, we show that the gradients of surface tension can induce particles to jet towards the oil/water interface with velocities as high as ≈ 60 mm/s when particle suspensions come in contact with the interface. We hypothesize that rubbing between the particles and oil lead to the spontaneous accumulation of negative charges on the hemisphere of those interfacial particles that contact the oil phase by means of triboelectrification. The charging process is highly dependent on the sliding distances, and gives rise to long-ranged repulsions that protect interfacial particles from coagulating at the interface by the presence of electrolyte. These triboelectric charges, however, are compensated within several hours, which affect the stability of interfacial particles. Importantly, by charging different kinds of colloidal particles using various spreading solvents and dispersion methods, we have demonstrated that charging and discharging of single colloidal particles at oil/water interfaces impacts a broad range of dynamical behavior.

No MeSH data available.


Related in: MedlinePlus

Charging of single colloidal particles at oil/water interfaces.Charging polystyrene microspheres (cyan bars) at an octane/10 mM NaCl interface using distinct suspensions: (a) containing different amounts of isopropanol ranging from 1 to 20%, (b) containing 5% methanol or ethanol or using pipetting for dispersions. Charging polymethylmethacrylate (red bar) or gold microspheres at an octane/10 mM NaCl interface, where the symbol (*) presents that the long-ranged repulsion had not been observed. (c) Cartoon schematically shows charging and discharging of single colloidal particles at an oil/water interface.
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f4: Charging of single colloidal particles at oil/water interfaces.Charging polystyrene microspheres (cyan bars) at an octane/10 mM NaCl interface using distinct suspensions: (a) containing different amounts of isopropanol ranging from 1 to 20%, (b) containing 5% methanol or ethanol or using pipetting for dispersions. Charging polymethylmethacrylate (red bar) or gold microspheres at an octane/10 mM NaCl interface, where the symbol (*) presents that the long-ranged repulsion had not been observed. (c) Cartoon schematically shows charging and discharging of single colloidal particles at an oil/water interface.

Mentions: Previous findings indicated that the gradients of surface tension would drive particles rubbing to the interface, which inspire us to conjecture that fast rubbing may induce the electrons transfer from one insulator (octane) to another (polystyrene microspheres). If yes, the quantity of residual charges building at interfacial particles should highly depend on the dispersion processes. Thus, we utilized aforementioned methods to evaluate the with distinctive dispersion conditions, including varying the isopropanol content in particles suspensions during the microinjection or directly pipetting particle suspensions to the interfaces (Fig. S7). Note that changing of isopropanol content from 1% to 20% in suspensions only slightly alters the wettability of particles at the interface (Fig. S8) because the isopropanol concentrations in our systems are very low27. Figure 4a indicated that are positively correlated to the content of isopropanol when the particles were injected to the interface, confirming that dispersion conditions strongly affect . Moreover, we find that the dispersion of particles by direct pipetting leads to less (Fig. 4b) comparing to that by microinjections.


Charging and discharging of single colloidal particles at oil/water interfaces.

Gao P, Xing X, Li Y, Ngai T, Jin F - Sci Rep (2014)

Charging of single colloidal particles at oil/water interfaces.Charging polystyrene microspheres (cyan bars) at an octane/10 mM NaCl interface using distinct suspensions: (a) containing different amounts of isopropanol ranging from 1 to 20%, (b) containing 5% methanol or ethanol or using pipetting for dispersions. Charging polymethylmethacrylate (red bar) or gold microspheres at an octane/10 mM NaCl interface, where the symbol (*) presents that the long-ranged repulsion had not been observed. (c) Cartoon schematically shows charging and discharging of single colloidal particles at an oil/water interface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4007091&req=5

f4: Charging of single colloidal particles at oil/water interfaces.Charging polystyrene microspheres (cyan bars) at an octane/10 mM NaCl interface using distinct suspensions: (a) containing different amounts of isopropanol ranging from 1 to 20%, (b) containing 5% methanol or ethanol or using pipetting for dispersions. Charging polymethylmethacrylate (red bar) or gold microspheres at an octane/10 mM NaCl interface, where the symbol (*) presents that the long-ranged repulsion had not been observed. (c) Cartoon schematically shows charging and discharging of single colloidal particles at an oil/water interface.
Mentions: Previous findings indicated that the gradients of surface tension would drive particles rubbing to the interface, which inspire us to conjecture that fast rubbing may induce the electrons transfer from one insulator (octane) to another (polystyrene microspheres). If yes, the quantity of residual charges building at interfacial particles should highly depend on the dispersion processes. Thus, we utilized aforementioned methods to evaluate the with distinctive dispersion conditions, including varying the isopropanol content in particles suspensions during the microinjection or directly pipetting particle suspensions to the interfaces (Fig. S7). Note that changing of isopropanol content from 1% to 20% in suspensions only slightly alters the wettability of particles at the interface (Fig. S8) because the isopropanol concentrations in our systems are very low27. Figure 4a indicated that are positively correlated to the content of isopropanol when the particles were injected to the interface, confirming that dispersion conditions strongly affect . Moreover, we find that the dispersion of particles by direct pipetting leads to less (Fig. 4b) comparing to that by microinjections.

Bottom Line: The charging process is highly dependent on the sliding distances, and gives rise to long-ranged repulsions that protect interfacial particles from coagulating at the interface by the presence of electrolyte.These triboelectric charges, however, are compensated within several hours, which affect the stability of interfacial particles.Importantly, by charging different kinds of colloidal particles using various spreading solvents and dispersion methods, we have demonstrated that charging and discharging of single colloidal particles at oil/water interfaces impacts a broad range of dynamical behavior.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, P. R. China 230026 [2].

ABSTRACT
The physical behavior of solid colloids trapped at a fluid-fluid interface remains in itself an open fundamental issue. Here, we show that the gradients of surface tension can induce particles to jet towards the oil/water interface with velocities as high as ≈ 60 mm/s when particle suspensions come in contact with the interface. We hypothesize that rubbing between the particles and oil lead to the spontaneous accumulation of negative charges on the hemisphere of those interfacial particles that contact the oil phase by means of triboelectrification. The charging process is highly dependent on the sliding distances, and gives rise to long-ranged repulsions that protect interfacial particles from coagulating at the interface by the presence of electrolyte. These triboelectric charges, however, are compensated within several hours, which affect the stability of interfacial particles. Importantly, by charging different kinds of colloidal particles using various spreading solvents and dispersion methods, we have demonstrated that charging and discharging of single colloidal particles at oil/water interfaces impacts a broad range of dynamical behavior.

No MeSH data available.


Related in: MedlinePlus