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  • Writer's pictureElina Isaeva

Nanoscale game-changers. Part 2: MWCNT (Multi-walled Carbon Nanotubes)

Nanoscale game-changers. Part 2: MWCNT (Multi-walled Carbon Nanotubes)

Carbon nanotubes (CNTs) are one of the most promising materials in modern science and technology. Among the various types of CNTs, multi-walled carbon nanotubes (MWCNT) deserve special attention, which stand out for their unique properties.

Multi-walled carbon nanotubes consist of several concentric cylinders formed by carbon atoms, each of which is a separate single-walled nanotube (Fig.1). These cylinders can contain up to several dozen walls, with the distance between the them being approximately 0.34 nm, which is close to the distance between the layers in graphite.

 

Figure 1. MWCNT (Multi-walled carbon nanotube) model
Figure 1. MWCNT (Multi-walled carbon nanotube) model

Figure 2. MWCNT (Multi-walled carbon nanotube) SEM image.
Figure 2. MWCNT (Multi-walled carbon nanotube) SEM image.

One of the key advantages of MWCNT is their high strength. These nanotubes are superior to many other materials, including steel and aluminum. The strength of MWCNT is explained by several factors at the chemical and physical level.

Carbon-carbon covalent bonds, which form the basis of nanotubes, are among the strongest in nature. These bonds provide high mechanical strength and resistance to fracture.

The presence of multiple walls improves mechanical stability. In the event of a defect or microcrack in one layer, other layers can compensate for the damage, preventing the complete destruction of the nanotube.

The "hoop" effect: The outer layers act as a kind of hoops, restraining the inner layers and preventing their deformation. This adds extra strength to the entire structure.

Single-walled carbon nanotubes (SWCNT) have unique electrical and thermal properties, but their mechanical strength is lower compared to MWCNT. SWCNT are more susceptible to damage due to a smaller number of structural walls, and even minor defects can significantly reduce their mechanical characteristics.

 

Application of MWCNT

MWCNT is used in various fields due to its outstanding properties. Here are some of the areas where they are used.

MWCNT are widely used to strengthen composite materials used in aviation, the space industry and the automotive industry. The addition of MWCNT significantly improves the mechanical properties of composites, increasing their strength, rigidity and resistance to wear. For example, composites with MWCNT are used in aircraft construction, where lightness and strength of materials are important.

In microelectronics and nanotechnology, MWCNT are used to create transistors, sensors and other electronic components. Their high conductivity and stability make them ideal for these purposes. MWCNT allow you to create more compact and efficient devices, such as flexible displays and highly sensitive sensors.

MWCNT is used in the production of batteries and supercapacitors. They increase the capacity and charging speed of devices due to their unique electrical properties. For example, batteries with MWCNT have increased capacity and durability, which is important for electric vehicles and mobile devices.

In medicine, MWCNT is used to develop new drug delivery methods, create biosensors, and develop materials for implants. Their unique structure makes it possible to create highly efficient drug delivery systems directly to the affected cells, minimizing side effects.

 

Many companies and research teams are actively engaged in the development and research of MWCNT.

A French company Arkema engaged in the production of nanomaterials is actively introducing MWCNT into its developments, including reinforcement of plastic and composite materials (Fig.2). Their products are used in various industries, from the automotive industry to consumer electronics, demonstrating high mechanical and electrical characteristics.


Figure 3. MWCNT in a polymer composite
Figure 3. MWCNT in a polymer composite

An American company Hyperion Catalysis International specializing in the production and application of carbon nanotubes, uses MWCNT to improve electrically conductive coatings and composites. The company's products are used in areas such as the production of antistatic coatings and conductive polymers, which opens up new opportunities for various industries.

A group of researchers at Rice University led by James Tour conducts advanced research in the field of synthesis and application of MWCNT, including their use in electronics and energy. They are developing new methods for producing high-quality nanotubes and exploring their application in creating more efficient batteries and supercapacitors.

 

The prospects for the development of MWCNT are very promising. There are several key trends that determine the future of this material:

The development of mass production methods will significantly reduce the cost of MWCNT, which will make them more accessible for a wide range of applications. Companies and research institutes are actively working to create more efficient and cost-effective synthesis technologies.

Current research is aimed at improving the properties of MWCNT by improving synthesis methods and developing new composite materials. For example, the addition of various functional groups to the surface of MWCNT can improve their compatibility with other materials and expand the scope of application.

In the future, we can expect to expand the range of applications of MWCNT in areas such as water treatment, environmental protection and the development of new medical technologies. For example, MWCNT -based filters can effectively remove impurities from water, and biosensors using them will help in the early diagnosis of diseases.

The combined use of MWCNT with other nanomaterials, such as graphene or quantum dots, can lead to the creation of materials with unique and excellent properties. These hybrid materials can be used in a wide variety of fields, from electronics to biomedicine.

 

Multi-walled carbon nanotubes are an important material with wide application possibilities in various industries. Their unique mechanical properties, especially their high strength, make them indispensable in the production of composites, electronics, energy and medicine. Modern developments and research continue to expand the horizons of using MWCNT, and the prospects for their further development promise new breakthroughs and achievements.

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