Researchers at the MIT - Massachusetts Institute of Technology used a lamination process to transfer graphene onto a broad variety of supple substrates without performing any intermediate steps or applying binding agents. This important achievement allows to overcome a number of issues concerning the interaction between graphene and other materials.
To bind graphene – a single layer of carbon atoms characterized by unique electronic and mechanical properties – to a target substrate, a polymer or some other interface should be used to act as binding agent. These, however, can often contaminate graphene and affect its properties.
On the other hand, the new technique designed by the team headed by Paulo Araujo and Jing Kong does not require any intermediate membrane or binding agent. The researchers started the process by synthesizing flakes of graphene on both sides of a copper foil (the standard approach used to obtain high-quality graphene). The flakes were then inserted between the selected supple surface and a layer of protective paper. The resulting “sandwich” was placed between two sheets of plastics and “passed” through a laminating machine at controlled temperature: thus the components were bound together. Lastly, the protective film and the plastic film were removed and the remaining material (i.e. the copper foil, the graphene sheet, and the target substrate) were soaked in a substance that completely dissolved the copper foil.
This system works without the contaminants used in traditional procedures. “Our technique could help produce high-quality supple touch screens, filtering membranes for gases or liquids, and graphene-based solar cells, just to mention a few possible applications,” says Araujo.
This is an important step, but more efforts are required. “While we have demonstrated that transfer without residues is possible, the resulting film should be more continuous,” says Luiz Pimenta, member of the research team. “The lack of continuity is welcome in certain applications, such as filters, much less in high-quality touch screen devices.”
Click here to read the abstract.,
The Editorial Staff
Published on Tuesday, November 5, 2013