Image Credit: N.Hanacek/NIST. Unlike other gel-creation approaches, where nanoparticles remain at the interface between the gel’s two constituent solvents (top left), the new approach concentrates nanoparticles in the interior of one of the solvents (top right), giving the resulting “SeedGel” unusual mechanical strength. The method could lead to gels that could be manufactured at industrial scales for a wide variety of potential applications.
Oil and water may not mix, but adding the right nanoparticles to the recipe can convert these two immiscible fluids into an exotic gel with uses ranging from batteries to water filters to tint-changing smart windows.
Scientists at the National Institute of Standards and Technology and the University of Delaware have found what appears to be a better way to create these gels, which have been an area of intense research focus for more than a decade.
These channels not only offer passageways for other materials to travel through, making them useful for filtration, but also give the gel a high amount of internal surface area, a characteristic valuable for speeding up chemical reactions or as scaffolding on which living tissue can grow.
While these and other advantages make it sound like gel innovators have struck oil, their creations have not yet mixed well with the marketplace.
The gels are commonly formed of two liquid solvents mingled together. Carefully cooking these ingredients allows a cohesive gel to form.
The process is demanding because custom-designing nanoparticles for each application has been difficult, and forming the gels has required carefully controlled rapid temperature change. These constraints have made it hard to create this type of gel in any more than small quantities suitable for lab experiments rather than on an industrial scale.
Its novel approach forms what the researchers refer to as a “SeedGel,” an abbreviation for “Solvent segregation driven gel.” Instead of designing nanoparticles to remain at the interface between the two solvents, their chosen particles concentrate within one of them.
The resulting gel could be far easier to create, as its two solvents are essentially oil and water, and its nanoparticles are silicon dioxide – essentially tiny spheres of common quartz.
Liu Yuyin Xi also said that the creation approach allows for the size of the channels within the gel to be tuned by changing the rate at which the temperature changes during the formation process, offering application designers another degree of freedom to explore. “It greatly extends the applications of these sorts of gels.”
Paper: Y. Xi, R.S. Lankone, L-P. Sung and Y. Liu. Tunable thermo-reversible bicontinuous nanoparticle gel driven by the binary solvent segregation. Nature Communications. Feb. 10, 2021.