Hot flames are essential for producing many materials. However, controlling fire and interacting with target substances can be difficult. Scientists have now developed a method to control how the heat of a flame interacts with a material using a protective layer as thin as a molecule. This puts the fire out and allows the user to fine-tune the properties of the processed material.
“Fire is a valuable engineering tool. After all, a blast furnace is just a fiery fire,” said Martin Tuo, a professor of materials science and engineering at North Carolina State University and the corresponding author of the paper on the study. To tell. “However, once a fire is started, it is often very difficult to control its behavior.
“With our technology called Inverse Thermal Degradation (ITD), nano scale Forms a thin film on the target substance. The membrane changes in response to the heat of the fire, regulating the amount of oxygen accessible to the material. This means that you can control the heating rate of the material and influence the chemical reactions that occur within the material. Basically, you can tweak where and how the fire transforms materials. ”
Here’s how ITD works: Start with a target material, such as cellulose fibres. The fibers are then coated with a nanometer-thick layer of molecules. The coated fibers are then exposed to a violent flame. The outer surface of the molecule burns easily, raising the temperature in the immediate vicinity. However, the inner surface of the molecular coating is chemically altered to form an even thinner layer of glass around the cellulose fibers. This glass limits the amount of oxygen that can access the fibers and prevents the cellulose from exploding. Instead, the fibers smolder and slowly flare from the inside out.
“Without the protective layer of ITD, burning the cellulose fibers just produces ash,” says Tuo. “With the ITD protective layer, you end up with a carbon tube.
“We can design the protective layer to tailor the amount of oxygen that reaches the target material, and we can design the target material to produce the desired properties.”
Researchers conducted a proof-of-concept demonstration of using cellulose fibers to fabricate microscale carbon tubes.
The researchers were able to control the wall thickness of the carbon tubes by controlling the size of the cellulose fibers. By introducing different salts into the fibers (further controlling the burning rate), by varying the amount of oxygen that passes through the protective layer.
“We already have some applications in mind that we will address in future research,” says Tuo. “We are also open to working with the private sector to explore various practical applications, such as the development of man-made carbon tubes for oil-water separation that are useful for both industrial applications and environmental remediation.”
Reference: “Spatially directed pyrolysis with thermomorphing surface adducts” Chuanshen Du, Paul Gregory, Dhanush U. Jamadgni, Alana M. Pauls, Julia J. Chang, Rick W. Dorn, Andrew Martin, E. Johan Foster, Aaron J. Rossini and Martin Tuo, 19 July 2023, Angewante Chemie.
DOI: 10.1002/anie.202308822