Felix Schacher of the Friedrich Schiller University Jena. Photo: Anne Günther/University of Jena.
Felix Schacher of the Friedrich Schiller University Jena. Photo: Anne Günther/University of Jena.

Researchers at the Friedrich Schiller University Jena and the Friedrich Alexander University Erlangen-Nuremberg, both in Germany, have successfully developed nanomaterials using a so-called bottom-up approach, by exploiting the fact that crystals often grow in a specific direction during crystallization. The resulting nanostructures, which appear as worm-like and decorated rods, could be used in various technological applications. The researchers report their work in a paper in ACS Nano.

“Our structures could be described as worm-like rods with decorations,” says Felix Schacher, professor of organic chemistry at the Friedrich Schiller University Jena. “Embedded in these rods are spherical nanoparticles; in our case, this was silica. However, instead of silica, conductive nanoparticles or semiconductors could also be used – or even mixtures, which can be selectively distributed in the nanocrystals using our method.” As such, the range of possible applications for these nanostructures in science and technology is broad, spanning from information processing to catalysis.

“The primary focus of this work was to understand the preparation method as such,” Schacher explains. To produce nanostructures, there are two different approaches: larger particles can be ground down to nanometer size, or the structures can be built up from smaller components. “We wanted to understand and control this building-up process.” For this, the team took individual silicon dioxide particles, known as silica, and grafted chain-like polymer molecules onto them as a sort of shell.

“One could imagine it like hairs on a sphere. These hairs are made of a material called poly-(isopropyl-oxazoline). This substance crystallizes when heated. And that's the idea of our method: crystals almost never grow in all directions simultaneously but prefer a particular direction. This is known as anisotropy. Thus, we were able to grow our nanostructures deliberately.”

During this process, the team discovered an intriguing phenomenon. “For the polymer to crystallize, it requires tiny amounts that are not bound to a particle surface but are freely present in the reaction solution, acting as a sort of glue,’ Schacher says. “We found out that the required amounts are so small that they are barely detectable. But they are needed.”

He is particularly excited about the unique collaboration that made this research possible: “Without the excellent cooperation with Prof. Michael Engel from the University of Erlangen, this work would not have been accomplished.”

“With the help of computer simulations that depicted behaviour across multiple scales, we were able to intricately resolve the complex molecular processes underlying the formation of the nanostructures,” says Engel. “This was an exciting challenge.”

This story is adapted from material from the Friedrich Schiller University Jena, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.