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Pickering emulsion disc particles1/17/2024 Modify-then-exfoliate is more efficient than the mask-and-modify method as it allows bulk reactions rather that limiting reactions to a two-dimensional interface. Masking can be achieved on either emulsion interfaces 24 or solid substrates 25, but regardless of procedure, reaction can be carried out only at the interface, rendering these methods tedious and not suitable for practical use. Mask-and-modify is a very common strategy for Janus platelet synthesis 23. Although the amphiphilic platelets have the potential to be used to stabilize emulsion, the current synthesis methods for such platelets is not reliable. Such amphiphilic structure of a nanoplate is also known as a Janus platelet, which has been previously reported by our group 21, 22. To minimize interfacial tension, asymmetric surface modification may be applied to satisfy different wetting preferences on corresponding sides of the platelet. Interfacial energy, in turn, is related not only to particle geometry, but is also controlled by surface wetting property. These merits contribute to the enhanced emulsion stability.Įmulsion stability varies directly with interfacial energy, a characteristic which has been well analyzed in other peer works 19, 20. Lastly, the two-dimensional configuration has higher efficiency in terms of material utilization compared to spherical or cylindrical geometries 18. Also, the large surface coverage area significantly increases the magnitude of energy required to remove platelets from the interface. There are several merits for doing so: firstly, the two-dimensional sheets can provide greater surface coverage than other configurations, which can prevent the emulsified phase from diffusing to the continuous phase. Among different particle morphologies, the idea of applying two-dimensional disks or platelets to stabilize emulsion attracts more attention 15, 16, 17. In related research, a variety of nanoparticles with different morphologies have been used to stabilize Pickering emulsions, such as zero-dimensional nanoparticles 12, one-dimensional nanowires 13, and one-dimensional nanotubes 14. Compared to emulsions stabilized by conventional molecular surfactants, Pickering emulsions are more stable due to their resistance to coalescence and Oswald ripening 3, 4, 5, which makes them perfect candidates for industrial application in foods 6, 7, mining 8, 9, pharmaceuticals 10 and cosmetics 11. The structures of Pickering emulsions and foams are stabilized with solid particles instead of molecular surfactants. Particle-stabilized emulsion, also known as Pickering emulsion, might provide a solution 2. Conventional EOR is carried out with molecular surfactants however, harsh formation conditions, such as high temperature or high salinity, can decrease the efficiency of molecular surfactants or polymer systems. Enhanced oil recovery (EOR) is a common well stimulation method to increase productivity of oil wells. Unless certain stimulation measures are taken, production on an aged well will be less economically viable for oil recovery. On the production side, production from aging wells will be reduced from current levels. Energy Information Administration’s (EIA) projection, fossil fuels will supply 75 quadrillion (10 15) BTU of energy by 2050 to meet the world energy demand 1. Similar content being viewed by othersĭespite the development of renewable energy sources, fossil fuel will remain as the dominant energy resource in the global energy supply for decades. This research provides important insights for the design and synthesis of two-dimensional Janus colloidal surfactants, which could be utilized in biomedical, food and mining industries, especially for circumstances where high salinity and high temperature are involved. Furthermore, we demonstrate the application of JNPS for enhanced oil recovery with a microfluidic flooding test, showing a dramatic increase of oil recovery ratio. The phase behaviors of water/oil emulsion generated by these novel platelet surfactants were also investigated. The microstructural characterization of solidified polystyrene emulsions indicates that the emulsion interface is evenly covered by JNPS. Such colloidal surfactants are found to be able to stabilize Pickering emulsions of different oil/water systems. Here we report a straightforward and cost-efficient strategy to develop Janus nanoplate surfactants (JNPS) from an aluminosilicate nanoclay, halloysite, by stepwise surface modification, including an innovative selective surface modification step. Combining the advantages of molecular surfactants and particle-stabilized Pickering emulsions, Janus colloidal surfactants generate remarkably stable emulsions. Janus colloidal surfactants with opposing wettabilities are receiving attention for their practical application in industry.
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