Physicists from Southern Federal University have proposed an original method to find organic molecules and polymers suitable for classification into single-walled carbon nanotubes.
Carbon nanotubes (CNTs) are synthetic materials with unique strength, electrical and thermal properties that enable a wide range of applications. Carbon nanotubes have captured the attention of scientists since the first studies were published in the distant 1950s, but the real boom in nanotubes occurred following the work of Juno Iijima in 1991, who studied multi-walled carbon nanotubes The atomic structure proves that the simplest single-walled nanotube is composed of defect-free graphene sheets curled together by a hexagonal honeycomb of carbon atoms .
However, there may be hundreds of these various tubular structures, even if their diameter is limited to a few nanometers. This diversity arises because adjacent honeycombs in the nanotube form spirals, and the pitch of these spirals relative to the nanotube axis and the diameter of the nanotube can vary greatly.
Regardless of their structure, carbon nanotubes are rigid and strong, and their bundles have very large surface areas per unit volume. This carbon nanomaterial could therefore be used both to enhance various objects and in batteries and other devices, where it is important to have a large internal surface area to deposit metal ions.
However, the structure of carbon nanotubes completely determines its electronic and other physical and chemical properties. This is why single-walled nanotubes with specific structures are needed in areas such as microelectronics, solar energy and medicine. For example, metal nanotubes are suitable as nanoconductors, and semiconductor nanotubes are suitable as nanotransistors and various nanosensors.
uses traditional synthesis methods to simultaneously form a variety of nanotubes with different diameters and wall structures. Synthesizing carbon nanotubes with the desired properties in one go is difficult and time-consuming. At the same time, it is much easier to obtain mixtures of nanotubes with different structures. This mixture is now available from many manufacturers. Therefore, scientists are actively developing techniques for sorting nanotubes with the desired (application-specific) structure and corresponding physical properties.
works on a scientific project funded by the Russian Foundation for Basic Research, under the supervision of Daria Roshal, member of the Faculty of Physics of Southern Federal University, Assistant at the Department of Theoretical and Computational Physics, and Principal Investigator Olga Konevtsova PhD in Physical and Mathematical Sciences , Professor Sergey Roshal of the Department of Nanotechnology proposed a theory that illustrates the physical and chemical laws that result from the classification of single-walled carbon nanotubes (SWCNTs) by those organic molecules that self-organize into regular coatings. Nanotubes and graphene. The theory proposed by
uses the concept of moiré patterns, which we can even see in our homes when two layers of translucent curtains are layered on top of each other. In modern physics, Moire patterns are used to explain the physical properties of multilayer structures. However, as the SFedU researchers have shown, this method is useful for finding organic molecules suitable for sorting carbon nanotubes.
Sergey Roshal, Ph.D. in Physical and Mathematical Sciences, Professor at the Department of Nanotechnology
"Using the experimental fact that some organic molecules can form coatings on flat graphene and nanotubes, we have reduced the conditions for successful classification to the analysis of double-walled nanotube layers for the first time. The outer layers in the proposed theory are virtual and their structure depends on the fact that the molecules considered form a regular coating on flat graphene," says Sergey Roshal.
In these tubes, the inner layer corresponds to the surface of the classified SWCNT, according to the scientists. The outer virtual layer is a honeycomb-like lattice rolled into a tube, onto whose surface the molecular arrangements characteristic of the planar shell can be projected.
"We also applied our method to explain the results of SWCNT sorting by polymers. Hypothesizing how the polymer core lies on a flat graphene layer, we explained the experimental results of SWCNT sorting by polymer molecular chains.Note that our method can also predict other organic molecules suitable for efficient sorting of CNT," says Olga Konevtsova, who proposed the main idea of the method. The article is published in the journal Nano Futures.
