Abstract:Back and forth: The CO2 /N2 trigger of a switchable surfactant (neutral amidine/cationic amidinium) was transferred to mineral nanoparticles through in situ hydrophobization in water. Switchable oil-in-water Pickering emulsions that entail a CO2 /N2 trigger were obtained by using negatively charged silica nanoparticles and a trace amount of the switchable surfactant as the stabilizer.
“…16 CO 2 has been reported as a smart gas to control the transition in the literature. 18,19 The main problem of using fatty acids is their insolubility in aqueous solution. Common alkalis such as NaOH and KOH usually dissolve fatty acids at high temperature with a high Krafft point.…”
Fatty acids, as a typical example of stearic acid, are a kind of cheap surfactant and have important applications. The challenging problem of industrial applications is their solubility. Herein, three organic amines-ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA)-were used as counterions to increase the solubility of stearic acid, and the phase behaviors were investigated systematically. The phase diagrams were delineated at 25 and 50 °C, respectively. The phase-transition temperature was measured by differential scanning calorimetry (DSC) measurements, and the microstructures were vesicles and planar sheets observed by cryogenic transmission electron microscopy (cryo-TEM) observations. The apparent viscosity of the samples was determined by rheological characterizations. The values, rcmc, for the three systems were less than 30 mN·m(-1). Typical samples of bilayers used as foaming agents and emulsifiers were investigated for the foaming and emulsification assays. CO2 was introduced to change the solubility of stearic acid, inducing the transition of their surface activity and further achieving the goal of defoaming and demulsification.
“…16 CO 2 has been reported as a smart gas to control the transition in the literature. 18,19 The main problem of using fatty acids is their insolubility in aqueous solution. Common alkalis such as NaOH and KOH usually dissolve fatty acids at high temperature with a high Krafft point.…”
Fatty acids, as a typical example of stearic acid, are a kind of cheap surfactant and have important applications. The challenging problem of industrial applications is their solubility. Herein, three organic amines-ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA)-were used as counterions to increase the solubility of stearic acid, and the phase behaviors were investigated systematically. The phase diagrams were delineated at 25 and 50 °C, respectively. The phase-transition temperature was measured by differential scanning calorimetry (DSC) measurements, and the microstructures were vesicles and planar sheets observed by cryogenic transmission electron microscopy (cryo-TEM) observations. The apparent viscosity of the samples was determined by rheological characterizations. The values, rcmc, for the three systems were less than 30 mN·m(-1). Typical samples of bilayers used as foaming agents and emulsifiers were investigated for the foaming and emulsification assays. CO2 was introduced to change the solubility of stearic acid, inducing the transition of their surface activity and further achieving the goal of defoaming and demulsification.
“…13 The potential applications of Pickering emulsion include drug delivery, oil recovery, food, material fabrication, and personal products. 14−16 Various solid particles have been employed for preparing Pickering emulsion, such as silica, 17 iron oxide, 18 clay, 19 polystyrene, 20 chitin nanocrystals, 21 and carbon black. 22 In addition, one of the exciting features of Pickering emulsion is that they are highly stable to coalescence even when the oil droplets are large.…”
The potential toxicity of existing chemical dispersants on the marine environment has motivated the search for environmentally friendly dispersants with excellent dispersion ability. Here, an effective Pickering emulsifier is developed based on the synergy of natural biopolymer, Xanthan Gum (XG), and silica nanoparticles. The oil−in−seawater emulsion stabilized by a combination of XG and silica demonstrates great stability and smaller droplet size, which is favorable for the following natural degradation of oil. The synergistic emulsification mechanism has been investigated systematically. The presence of XG favors the adsorption of silica nanoparticles at the oil−seawater interface and also is considerably effective in enhancing the viscosity of continuous phase. These contributions of XG slow down the droplet coalescence and creaming significantly. Confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) images of emulsions indicate a thick layer of aggregated XG/silica particles at the oil− water interface. This thick layer provides an effective steric barrier. In this study, the synergy between XG and silica not only enhances the dispersion effectiveness, but also reduces the amount of nanoparticles dramatically. This finding opens up a new path for the development of a novel, high efficiency, ecologically acceptable, and cheaper dispersant for emulsifying crude oil following a spill.
“…1 Because of the strong steric repulsion of particle layers at the interface, solid-stabilized emulsions ( , porous materials 4 , core shell materials 5 , nanocomposites 6,7 , and colloidosomes 8-10 and designing smart emulsion systems 11,12 .…”
Section: Introductionmentioning
confidence: 99%
“…So usually modification of particles is necessary. Generally, in situ surface modification with surfactant is used as a preferable alternative considering its simplicity and low cost 12 .Thus, the understanding of the behavior of emulsion stabilized by mixture of inorganic particles and surfactant is crucial.…”
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