Oil and water may not mix, but with the addition of the appropriate nanoparticles to the recipe, these two immiscible liquids can be exotic gels for a variety of applications, from batteries to water purifiers to smart windows that change shades. Can be converted to. A new approach to creating this unusual class of soft materials allows them to be brought to market from the laboratory.
Scientists at the National Institute of Standards and Technology (NIST) and the University of Delaware have discovered what appears to be a better way to make these gels. These gels have been the focus of intensive research for over a decade. Part of their potentially widespread utility is the complex set of interconnected microchannels that form within them and create sponge-like structures. These channels provide a passage for other materials to pass through, which not only helps with filtration, but also gives the gel a large amount of internal surface area. This is a valuable property for accelerating chemical reactions or as a scaffold for living tissue to grow.
These and other benefits sound like gel innovators have hit oil, but their creations haven’t mixed well with the market yet. Gels are usually formed by mixing two liquid solvents. Like oil and water, these solvents do not mix well, but to prevent complete separation, researchers add custom-designed nanoparticles that can stay at the interface between them. Careful cooking of these ingredients results in the formation of cohesive gels. However, custom designing nanoparticles for each application is difficult, and the process is demanding because gel formation requires rapidly controlled and rapid temperature changes. These constraints make it difficult to produce this type of gel in small quantities or more, suitable for laboratory experiments rather than on an industrial scale.
As explained in New Nature Communications The paper, the NIST / Delaware team, has found a way around many of these issues. That novel approach forms what researchers call “seed gel,” which is an abbreviation for “solvent separation-driven gel.” Instead of designing the nanoparticles to stay at the interface between the two solvents, those selected particles concentrate on one of them. Although these particles tend to repel each other, they have a stronger affinity for one of the solvents, keeping them together in the channel. The team has clearly demonstrated that they have successfully concentrated the nanoparticles where they are needed using the NIST Center for Neutron Research (NCNR) neutron scattering tools.
The resulting gel is much easier to make because the two solvents are essentially oil and water and the nanoparticles are silicon dioxide (essentially small spheres of common quartz). I will. It also has a variety of industrial uses.
“Our SeedGel has excellent mechanical strength, is much easier to manufacture, and the process can be extended to meet the needs of the manufacturer,” said NCNR scientist and associate professor at the University of Delaware. But Yun Liu said. “In addition, it is thermoreversible.”
This reversibility refers to the optical properties of the finished SeedGel. You can switch from transparent to opaque and back to normal simply by changing the temperature. This property is available in smart windows that sandwich a thin layer of gel between two glass plates.
“This optical property may make SeedGel useful in other photosensitive applications,” said Yuyin Xi, a researcher at the University of Delaware who works at NCNR. “They can be useful for sensors.”
The team’s gel-making approach can be used in combination with other solvents and nanoparticles, which can be useful in water purification filters and, in some cases, other filtration processes, depending on the type of nanoparticles used.
Liu also states that the creation approach allows application designers to explore freely by adjusting the size of the channels in the gel by changing the rate at which the temperature changes during the formation process.
“Our approach is a general approach that works for many different nanoparticles and solvents,” he said. “This greatly expands the use of this type of gel.”
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Yuyin Xi et al, Adjustable thermoreversible bicontinuous nanoparticle gel driven by two-component solvent separation, Nature Communications (2021). DOI: 10.1038 / s41467-020-20701-3
Provided by National Institute of Standards and Technology
This story has been republished in courtesy of NIST. Read the original story here.
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Nanoparticle gels combine oil and water with a manufacturing-friendly approach
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