Left and center: magnetite- and gold-based nanoparticles self-assemble into lattice-like structures. Right: individual gold- and magnetite-based nanoparticles. Images: Petr Kral.A collaborative group of researchers including Petr Kral, professor of chemistry at the University of Illinois at Chicago, has developed a new technique for creating novel nanoporous materials with unique properties that can be used to filter molecules or light. They describe their research in a paper in Science.
These nanoporous materials are made up of nanoparticles comprising a central solid core to which molecules called ligands can be attached. This allows the nanoparticles to self-assemble into lattice-like formations that possess unique optical, magnetic, electronic and catalytic properties.
Led by Rafal Klajn, professor of chemistry at the Weizmann Institute of Science in Israel and corresponding author on the paper, the researchers produced thin lattice structures made up of two kinds of nanoparticle: one with a magnetite core and the other with a gold core. In order to form the thin, lattice-like structures, the researchers induced the nanoparticles to self-assemble within a layer of drying solvent floating on another liquid in which the particles are insoluble.
"The self-assembly mechanisms in the thin solvent layer differ from those at work when nanoparticles are allowed to self-assemble in bulk solvents," Kral explained.
The researchers also developed a technique for chemically removing one of the two types of nanoparticles from the self-assembled, lattice-like structures to produce a material with tiny, regularly spaced holes. They then turned to Kral's theoretical chemistry group, which included Lela Vukovic, assistant professor of chemistry at the University of Texas at El Paso, to help them understand how these lattices formed.
Kral and Vukovic used atomistic molecular dynamics simulations to model exactly how the two different nanoparticles self-assembled into the thin, lattice-like structures. They found that, depending on the type of liquids used in this process, the nanoparticles could form different structures.
"Based on the known properties of the nanoparticles and the different liquid surfaces they were placed onto, we were able to predict how and why different lattices formed," said Kral, whose group has extensively studied how nanoparticles interact to form complex superstructures.
By changing the composition of the nanoparticles and the liquids on which they self-assemble, Kral said chemists can create a huge number and variety of new nanoporous materials. Different sized nanoparticles would, when removed, create different pore sizes.
This story is adapted from material from the University of Illinois at Chicago, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.