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B P Binks - One of the best experts on this subject based on the ideXlab platform.
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Phase Inversion of Silica Particle-Stabilized Water-in-Water Emulsions
2019Co-Authors: B P Binks, Hui ShiAbstract:An aqueous two-phase system (ATPS) is of great value in low calorie foods or oil-free cosmetics and pharmaceuticals. In contrast to the recent work on polymer/polymer ATPSs, a simple polymer/salt ATPS (polyethylene glycol/Na2SO4) was chosen to study water-in-water (w/w) emulsions stabilized by solid Particles. The binodal curve and the tie lines were first determined for the mixture at room temperature. Above the binodal curve, two water-based phases coexist; the upper phase is rich in polymer, whereas the lower phase is rich in salt. Within the two-phase region, we attempted to prepare w/w emulsions with or without the addition of common emulsifiers. Ionic and nonionic surfactants, a polymer, and various solid Particles (hydrophilic calcium carbonate Particles of different sizes and shapes, wax microspheres) were selected, but no stable emulsion was possible. However, stable w/w emulsions of both types (polymer-in-salt and salt-in-polymer) were formed using dichlorodimethylsilane-modified nanoSilica Particles. Using partially hydrophobic fumed Silica as the emulsifier, emulsions remained fully emulsified for over 1 year and we link the extent of hydrophobization of Particles to the properties of the emulsions via contact angle measurements. Furthermore, systematic emulsion studies were conducted at different overall compositions such that changes in emulsion type and stability were mapped onto the phase diagram. Catastrophic phase inversion of emulsion type and evolution of emulsion stability were monitored along the tie lines. Importantly, stability to coalescence was found to decrease approaching conditions of phase inversion
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effect of Particle hydrophobicity on the properties of Silica Particle layers at the air water interface
Langmuir, 2007Co-Authors: M Safouane, D Langevin, B P BinksAbstract:This article describes a study of fumed Silica Particle layers adsorbed at the air−water interface. We have performed surface pressure, ellipsometry, and Brewster angle microscopy measurements. These determinations were complemented by surface viscoelasticity studies, using capillary waves to measure the compression moduli and an oscillating disc to measure the shear moduli. Our results show a strong influence of the Particle hydrophobicity and surface density on the properties of the layers. Under compression−expansion, the Particle layers rearrange quasi-instantaneously, and at high density, they buckle and/or collapse. Shear measurements show a transition from viscous to elastic behavior for Particles with contact angles close to 90°. The surface compression moduli are quite small and most likely not related to the stability of the foams made with these Particles, in contrast to the case of more common surfactant foams.
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effect of Particle hydrophobicity on the formation and collapse of fumed Silica Particle monolayers at the oil water interface
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006Co-Authors: Tommy S Horozov, B P Binks, Robert Aveyard, John H ClintAbstract:Abstract Monolayers of fumed Silica Particles at the octane–water interface have been studied by compression–expansion experiments in a Langmuir trough and simultaneous microscope observations. Particle hydrophobicity has been varied in a broad range, from hydrophilic to very hydrophobic, and its effect on the formation, surface pressure and collapse of monolayers has been investigated. A strong influence of Particle hydrophobicity on the degree of Particle attachment to the oil–water interface has been found in accord with the existing theory for the effect of Particle hydrophobicity (wettability) on the free energy of Particle attachment. It is shown that fumed Silica Particle monolayers collapse by buckling which begins in the region of fastest increase of the surface pressure, just after the inflection point of the surface pressure–area curves. This unusual buckling behaviour has been attributed to the ability of fumed Silica Particles to form network structures as a result of the capillary attraction typical for Particles with non-spherical shape and irregular (undulated) three phase contact line. An interesting coexistence of ripples with two very different wavelengths is observed in collapsed monolayers which has not been reported before. Surface pressure–area isotherms for monolayers of Particles with different hydrophobicity are compared and information about the effect of Particle hydrophobicity on Particle interactions at an oil–water interface is obtained.
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structure and stability of Silica Particle monolayers at horizontal and vertical octane water interfaces
Langmuir, 2005Co-Authors: Tommy S Horozov, B P Binks, Robert Aveyard, John H ClintAbstract:Monolayers of Silica Particles at horizontal and vertical octane−water interfaces have been studied by microscopy. It is found that their structure and stability depend strongly on the Particle hydrophobicity. Very hydrophobic Silica Particles, with a contact angle of 152° measured through the water, give well-ordered monolayers at interParticle distances larger than 5 Particle diameters which are stable toward aggregation and sedimentation. In contrast, monolayers of less-hydrophobic Particles are disordered and unstable. Two-dimensional Particle sedimentation has been observed in the case of vertical monolayers. The results have been analyzed with a simple two-Particle model considering the sedimentation equilibrium as a balance between the long-range electrostatic repulsion through the oil, the gravity force, and the capillary attraction due to deformation of the fluid interface around Particles. The value of the charge density at the Particle−octane interface, 14.1 μC/m2, found for the most hydrophobi...
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Silica Particle stabilized emulsions of silicone oil and water aspects of emulsification
Langmuir, 2004Co-Authors: B P Binks, Catherine P WhitbyAbstract:A study of the emulsification of silicone oil and water in the presence of partially hydrophobic, monodisperse Silica nanoParticles is described. Emulsification involves the fragmentation of bulk liquids and the resulting large drops and the coalescence of some of those drops. The influence of Particle concentration, oil/water ratio, and emulsification time on the relative extents of fragmentation and coalescence during the formation of emulsions, prepared using either batch or continuous methods, has been investigated. For batch emulsions, the average drop diameter decreases with increasing Particle concentration as the extent of limited coalescence is reduced. Increasing the oil volume fraction in the emulsion at fixed aqueous Particle concentration results in an increase in the average drop diameter together with a dramatic lowering of the uniformity of the drop size distribution as coalescence becomes increasingly significant until catastrophic phase inversion occurs. For low oil volume fractions (φo)...
Jennifer A Lewis - One of the best experts on this subject based on the ideXlab platform.
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visualization and simulation of the transfer process of index matched Silica microParticle inks for gravure printing
Aiche Journal, 2017Co-Authors: Arnout Boelens, Sooman Lim, Lorraine F. Francis, Bok Yeop Ahn, Juan J De Pablo, Jennifer A LewisAbstract:A combined experimental and computational study of the transfer of transparent index-matched Silica-Particle inks between two flat plates is presented for gravure printing applications. The influence of printing speed and initial ink droplet size on the ability to accurately transfer ink during the printing process is explored systematically. Smooth interface volume of fluid simulations show the same trends as the ink transfer observed in experiments over a wide range of printing speeds and for inks having different Silica Particle loadings. Our calculations indicate that for ink droplets with characteristic dimensions in the vicinity of 10 μm, which are of particular interest for gravure printing applications, ink transfer improves significantly due to the diminishing effect of gravity, and the increased importance of capillary forces at small length scales. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1419–1429, 2017
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Visualization and simulation of the transfer process of index‐matched Silica microParticle inks for gravure printing
Aiche Journal, 2016Co-Authors: Arnout Boelens, Sooman Lim, Lorraine F. Francis, Bok Yeop Ahn, Juan J De Pablo, Jennifer A LewisAbstract:A combined experimental and computational study of the transfer of transparent index-matched Silica-Particle inks between two flat plates is presented for gravure printing applications. The influence of printing speed and initial ink droplet size on the ability to accurately transfer ink during the printing process is explored systematically. Smooth interface volume of fluid simulations show the same trends as the ink transfer observed in experiments over a wide range of printing speeds and for inks having different Silica Particle loadings. Our calculations indicate that for ink droplets with characteristic dimensions in the vicinity of 10 μm, which are of particular interest for gravure printing applications, ink transfer improves significantly due to the diminishing effect of gravity, and the increased importance of capillary forces at small length scales. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1419–1429, 2017
Minhua Jiang - One of the best experts on this subject based on the ideXlab platform.
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preparation of metal Silica core shell Particle films by interfacial self assembly
Journal of Colloid and Interface Science, 2010Co-Authors: Dongsheng Li, Yimin Wu, Hailong Li, Deren Yang, Minhua JiangAbstract:Abstract A universal self-assembly method is used to prepare a series of large-area Silica-coated metal Particle (metal@Silica) films at the hexane/water interface. The decrease of hexane/water interfacial energy after the Particle adsorption leads to the formation of films. Since external Silica shells eliminate the coupling between neighboring metal core Particles, the extinction peaks of closely packed metal@Silica Particle films are as narrow as those of monodispersed metal Particles. In the detection of Raman scattering signals of R6G dyes by shell-isolated nanoParticle-enhanced Raman spectroscopy, the use of metal@Silica Particle films resulted in an average enhancement by a factor of 105.
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Preparation of metal@Silica core-shell Particle films by interfacial self-assembly.
Journal of Colloid and Interface Science, 2010Co-Authors: Dongsheng Li, Yimin Wu, Hailong Li, Deren Yang, Minhua JiangAbstract:Abstract A universal self-assembly method is used to prepare a series of large-area Silica-coated metal Particle (metal@Silica) films at the hexane/water interface. The decrease of hexane/water interfacial energy after the Particle adsorption leads to the formation of films. Since external Silica shells eliminate the coupling between neighboring metal core Particles, the extinction peaks of closely packed metal@Silica Particle films are as narrow as those of monodispersed metal Particles. In the detection of Raman scattering signals of R6G dyes by shell-isolated nanoParticle-enhanced Raman spectroscopy, the use of metal@Silica Particle films resulted in an average enhancement by a factor of 105.
Soonchul Kwon - One of the best experts on this subject based on the ideXlab platform.
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fracture toughness of nano and micro spherical Silica Particle filled epoxy composites
Acta Materialia, 2008Co-Authors: Tadaharu Adachi, Mayuka Osaki, Wakako Araki, Soonchul KwonAbstract:The effects of Particle size and volume fraction on the mode I fracture toughness of epoxy composites filled with spherical Silica Particles were investigated through experiments and an analytical model. Spherical Silica Particles with various Particle diameters ranging from 1.56 μm to 240 nm and volume fractions from 0 to 0.35 were added to epoxy resin. We found that the fracture toughness of the composites was approximately linear with respect to the reciprocal of the product of (i) the square root of the mean distance between the Particle surfaces and (ii) the normalized mean stress in the matrix given by the equivalent inclusion method.
Shuji Hashimoto - One of the best experts on this subject based on the ideXlab platform.
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Adhesion of gels by Silica Particle.
The journal of physical chemistry. B, 2014Co-Authors: Hidekazu Abe, Yusuke Hara, Shingo Maeda, Shuji HashimotoAbstract:In this study, a method for achieving adhesion between two positively charged gels with high mechanical strength was developed. By utilizing a Silica Particle dispersion as a binder, the gels easily adhered to each other and remained stable for up to 11 days when immersed in aqueous solution. The adhesion force between the two positively charged semi-interpenetrating network gels with the Silica Particle was measured to be up to approximately 20 kPa, which is around 10 times larger than that with a charged polymer-rich liquid as a cross-linker (approximately 1.5 kPa). It was demonstrated that the adhesion force was a result of two types of interactions: an electrostatic attractive force between the cationic gel surface and hydrogen bonding among the Silica Particles. In addition, it was shown that the adhesion force was dependent on solution pH, which was attributed to changes in the charge of the Silica Particles.