Investigation of charging behavior of PS particles in nonpolar solvents

Cao, Huiying; Cheng, Yanhua; Huang, Pin‐Wen; Qi, M.

doi:10.1088/0957-4484/22/44/445709

Cited by 10 publications

(18 citation statements)

References 34 publications

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“…59 By following the motion of particles in an electric field, the effect applied in electronic paper displays, the sign of the surface charge can be extracted. Electrophoretic motion of hydrophobic particles in AOT has been measured using optical tweezer SPOM, 62,65,119 phase-analysis light scattering (PALS), 46,60,122 and differential-phase optical coherence tomography (DP-OCT). 63,69 These studies all agree that AOT induces a negative charge on hydrophobic surfaces and that the surface charge varies with surfactant concentration, although some studies find that the surface potential is constant.…”

Section: Hydrophobic Surfacesmentioning

confidence: 99%

“…61 For studies which examine the concentration dependence over a wide range, five or six orders of magnitude to include samples both with and without inverse micelles present, the value of ζ or µ is found to increase to a maximum, around 1 mM, when it either plateaus (in the case of ζ ) or begins to decrease (in the case of µ). 47,67,120,123 There have been fewer studies into charging hydrophobic surfaces with surfactants other than AOT, and the results do not agree as clearly. Span 85 surfactant was found to induce a positive charge on PMMA in hexane using PALS, except for low concentrations and high applied fields where the sign reverses.…”

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confidence: 99%

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Controlling colloid charge in nonpolar liquids with surfactants

Smith

Eastoe

2013

Phys. Chem. Chem. Phys.

100

146

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The formation of ions in nonpolar solvents (with relative permittivity ε r of approximately 2) is more difficult than in polar liquids; however, these charged species play an important role in many applications, such as electrophoretic displays. The low permittivities (ε r) of these solvents mean that charges have to be separated by large distances to be stable (approximately 28 nm or 40 times that in water). The inverse micelles formed by surfactants in these solvents provide an environment to stabilize ions and charges. Common surfactants used are sodium dioctylsulfosuccinate (Aerosol OT or AOT), polyisobutylene succinimide, sorbitan oleate, and zirconyl 2-ethyl hexanoate. The behavior of charged inverse micelles has been studied on both the bulk and on the microscopic scale and can be used to determine the motion of the micelles, their structure, and the nature of the electrostatic double layer. Colloidal particles are only weakly charged in the absence of surfactant, but in the presence of surfactants, many types, including polymers, metal oxides, carbon blacks, and pigments, have been observed to become positively or negatively charged. Several mechanisms have been proposed as the origin of surface charge, including acid-base reactions between the colloid and the inverse micelle, preferential adsorption of charged inverse micelles, or dissolution of surface species. While most studies vary only the concentration of surfactant, systematic variation of the particle surface chemistry or the surfactant structure have provided insight into the origin of charging in nonpolar liquids. By carefully varying system parameters and working to understand the interactions between surfactants and colloidal surfaces, further advances will be made leading to better understanding of the origin of charge and to the development of more effective surfactants.

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Section: Hydrophobic Surfacesmentioning

confidence: 99%

mentioning

confidence: 99%

Controlling colloid charge in nonpolar liquids with surfactants

Smith

Eastoe

2013

Phys. Chem. Chem. Phys.

100

146

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“…As is demonstrated in Figure 2c, the preferential adsorption of anionic inverse micelles on the surface of polymeric µ-spheres enables the charge stabilization of the µ-spheres in a non-polar medium. [14] The development of surface charge on the µ-spheres provides the formation for a stable colloidal dispersion as shown in Figure 2a. [9,14,15] In Figure 2d, the zeta potentials of the PtBMA µ-spheres and PMMA-PtBMA core-shell µ-spheres with similar diameters (200 nm) that were respectively dispersed in IPG/HC/AOT were measured with varying concentrations of AOT.…”

Section: Resultsmentioning

confidence: 99%

“…[14] The development of surface charge on the µ-spheres provides the formation for a stable colloidal dispersion as shown in Figure 2a. [9,14,15] In Figure 2d, the zeta potentials of the PtBMA µ-spheres and PMMA-PtBMA core-shell µ-spheres with similar diameters (200 nm) that were respectively dispersed in IPG/HC/AOT were measured with varying concentrations of AOT. Both of the µ-sphere systems exhibited the maximum surface potentials at approximately the 100-150 mm AOT concentration range.…”

Section: Resultsmentioning

confidence: 99%

Full‐Color Electrophoretic Display Using Charged Colloidal Arrays of Core–Shell Microspheres with Enhanced Color Tunability in Non‐Polar Medium

Park

Lee

Lee³

et al. 2021

Advanced Optical Materials

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In this study, core–shell microspheres of poly(methylmethacrylate) (PMMA) and poly(t‐butylmethacrylate) (PtBMA) are synthesized and dispersed in a non‐polar medium exhibiting a structural color in the visible range. The charge stabilization of the PMMA–PtBMA microsphere is achieved because of preferential adsorption of the charged inverse micelles of aerosol‐OT (AOT) on the microsphere surface. While the PtBMA shell enables the dispersion of the microspheres in isoparaffinic fluid, the PMMA core provides an enhanced refractive index contrast with the medium. In comparison to PtBMA‐only microsphere, incorporation of PMMA core not only increases the average refractive index but also increases the surface charge density of the microsphere, which is attributed to strong attraction between the inverse micelles and the microsphere. The optimized crystalline colloidal array (CCA) of the PMMA–PtBMA microsphere shows stronger structural colors than those of the PtBMA‐only spheres because of an enhanced index contrast with the liquid medium, and an improved color tunability is also achieved. A CCA exhibits approximately 50% light transmittance, demonstrating a semi‐transparent display. The repeated voltage biases proved that a CCA has excellent stability. Finally, a low‐angular dependency of the PMMA–PtBMA CCA is confirmed, which is an advantageous feature as an electrophoretic display.

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“…Recently, Binks et al 21 used surfactant SDS (sodium dodecyl sulfate) to successfully achieve the inversion of dry water to aqueous foam by changing the activation of silica surface particles in aqueous system, whereby the hydrophobic surface of the particle was converted into hydrophilic surface by adsorbing SDS molecules. AOT, an ionic surfactant with double carbon chain, was used as a usual charge control agent for particles charging in apolar dispersions 22,23 is considered for the activation of CaCO 3 nanoparticles and investigated their ability to stabilize aqueous foam. 24 Mineral oxide nanoparticles and cationic CTAB were investigated for their synergistic effect on stabilization of CO 2 foam for the application in enhanced oil recovery.…”

Section: Introductionmentioning

confidence: 99%