Scientists create nanomaterials using a bottom-up approach

Two scientists from Friedrich Schiller University Jena and Friedrich Alexander University Erlangen-Nuremberg in Germany have successfully developed nanomaterials using a bottom-up approach. As reported in the press ACS Nano, they take advantage of the fact that crystals often grow in a specific direction during crystallization. The resulting nanostructures can be used in a variety of technological applications.

„Our structures can be described as worm-like rods with decorations,” explains Professor Felix Schacher. „Embedded in these rods are spherical nanoparticles; in our case, this is silica. However, instead of silica, conductive nanoparticles or semiconductors or even compounds can be used, which can be selectively distributed in the nanocrystals using our method,” he adds. Accordingly, the range of potential applications in science and technology is extensive, spanning from information processing to catalysis.

Understanding and controlling the manufacturing process

„The primary focus of this work is to understand the production process,” explains the chemist. To create nanostructures, he elaborates, there are two different approaches: large particles are ground down to nanometer size, or structures are built from smaller components.

„We wanted to understand and control this building process,” explains Schacher. For this, the team used individual silicon dioxide particles called silica and attached chain-like polymer molecules as a kind of shell.

„One can imagine it like hairs in a sphere,” explains the scientist. He adds, „These hairs are made of a material called 'poly-(isopropyl-oxazoline)’. This material crystallizes when heated, and that’s the idea of ​​our method: the crystals don’t grow in almost all directions at once, but prefer a particular direction. This is called anisotropy.” Thus, we were able to deliberately grow our nanostructures.”

During this process, the team discovers a puzzling phenomenon. „For the polymer to crystallize, it needs small amounts that are not bound to a particle surface, but are free in the reaction solution, acting as a kind of glue. We found that the amounts needed are so small that they are barely detectable. But they are needed,” he adds.

Schachter is particularly excited about the unique collaboration that made this research possible. „Without the excellent collaboration with Professor Michael Engel from the University of Erlangen, this work would not have been possible,” emphasizes the scientist from Jena.

„With the help of computer simulations that depict behavior at multiple scales, we were able to intricately unravel the complex molecular processes underlying the formation of nanostructures. This was an exciting challenge,” adds Engel.

The two scientists conclude, „Earlier this year we had the opportunity to participate together in the Kavli Institute for Theoretical Physics (KITP) project at the University of California, Santa Barbara. During this workshop, we jointly wrote this manuscript. The fundamental experiments were funded by the German Research Foundation TRR 234 It was conducted somewhat earlier within the framework of the collaborative research center 'Catalyte’, but the stimulating atmosphere of the workshop gave us the necessary momentum to complete the work.”