New opportunities for nanotubes: a Polish recipe for nanomaterial sheets
– We have discovered how to prepare virtually any large, flexible sheet composed of nanomaterialsóIn carbon – that is, from nanotubes or graphene. And this with such properties as we happen to need – mówi in an interview with PAP Dawid Janas from the Silesian University of Technology. His team’s research was published in the journal "Materials and Design".
The researcher recalls in an interview with PAP that several methods of making such sheets from nanomaterials have previously existedóin carbon nanotubes, but none of them allowed to precisely control the structure of the carbon material and its properties. – In our method, we can prepare a sheet from precisely selected nanotubes – with exactly the properties we need – mówi.
Such low-cost, lightweight nanotube sheets could come in handy, he adds. In electronics – for heat dissipation in computers – instead of elementalóin copper – whether, for example. for de-icing aircraft wingsów.
Carbon nanotubes are tiny rolls of a single layer of carbon – something like graphene rolled up into a nanometer diameter tubeów (millionth of a millimeter). The properties of individual nanotubes are so unique that they raise high hopes among researchers. Although such structures have been known for more than twoóch decades, the problem has been how to use them. Although they are easy to produce, but there is a problem – the process produces a mixture of nanotubes with rótive properties. There are and nanotubes, whichóre conduct electricity better than copper, and nanotubes with the characteristics of półrzewodników, and nanotubes with high resistivity.
In such a "bigos" The unique properties of individualólnych nanotubes cease to matter. Only in the last 2-3 years has it been known how nanotubes can be segregated and separated spośród them those with desirable thermal, mechanical or electrical properties. Until now, however, there has not yet been a way to give such selected nanotubes spójna structure and obtain a flexible sheet from the powder.
And this is what researchers from the Silesian University of Technology managed to do. They showed how to turn a nanotube powder with uniform properties into a large sheet, którą np. can be superimposed on another surface. For now, the researchers have succeeded in obtaining A4-size sheets, but in a properly equipped laboratory it will be possible to produce sheets of any size, shape and thickness of your choice.
– So if, for example. We want to have material póA solid-state, whichóry will be useful for building elementsóin the computer, we are able to scoop out nanotubes with such properties and prepare a large sheet from them,” he said.
Recipe for nanotubes
Dr. Janas says the recipe for the nanotube sheet is very simple. We take black powder – that is, properly selected carbon nanomaterial – and mix it with white powder – ethyl cellulose, a binding agent used in the food industry. To this we add an organic solvent. In this wayób paint is formed.
Paint is sprayed onto plastic, e.g. polyethylene. It is created in this wayób a thin layer, która poorly adheres to the ground. The sheet can be detached from the substrate simply by bending it a few times.
To get rid of the ethyl cellulose, która is still in the sheet, the sheet just needs to be set on fire – even with a lighter. The ethyl cellulose from the whole sheet is burned off in a second or two. In this wayób we get a flexible, spójna sheet, whichóra is composed of the same nanotubes thatóre previously in the form of powder.
Nanotubes are a bit like long cables. The binding agent makes their structures entangle with each other, and even if the ethylcellulose is removed, the nanotubes already entangled remain.
Thinking outside the box
– It can be said that setting the sheet on fire with a lighter is a rather primitive method of getting rid of ethylcellulose. But very effective! We were very surprised that this polymer completely oxidizes, leaving no trace of theóin the material. And such fire is completely harmless to nanotubes or graphene, describes Dr. Janas.
– At first we looked for an ingredientów on nanotube paint, whichóra will be able to adhere well to our substrate. And we have produced a paint thatóra from the substrate comes off easily. We thought it was a problem. But then we started thinking more broadly,” he adds.
Janas leekówn that it was similar in the company, która worked on a super glue. By coincidence, a weak adhesive was developed there. However, instead of throwing the recipe in the trash – a use was found for it – sticky notes were invented. – We thought that maybe some custom applications could be found here as well,” he says. And adds that its compositeół have already come up with several such ideasóin, where flexible sheets of nanotubes will be more useful than a coating permanently bonded to the substrate.
According to Dr. Janas such a sheet of nanotubes can be e.g. use to dissipate heat from the laptopów. – There is a lot of copper in computers, whichóra m.in. dissipate heat from the processor, the researcher points out. According to him, if copper were replaced by a sheet of nanotubes there, it could prove to be both a cheaper and lighter solution.
– We also thought that such sheets of carbon nanostructures could be used, for example. for de-icing aircraft wingsów. Flexible sheets could, for example. put on the wings of an airplane, heat them electrically and thusób efficiently remove lód – reflects the researcher. He hopes to find companies interested in implementing these solutions.
Dr. Janas began his research on nanotubes at Cambridge University. Last year wróHe came to Poland as part of the POLONEZ program of the National Science Center.