What are Self-Healing Nanofibers?

What are self-healing nanofibers?

Nanofibers with self-healing properties are emerging as revolutionary materials for further advancement at the forefront of nanotechnology. This article discusses self-healing nanofibers, their background, applications in different industrial sectors and recent relevant studies.

Image Credit: Kateryna Kon/Shutterstock.com

Background

Materials scientists have spent the past decades working on improving various properties of materials. Consistent research and development has resulted in materials with improved performance. However, materials still deteriorate over time and experience operational fatigue, leading to nanocracks and eventual failure.

Most composites are vulnerable to micro-cracks that are very difficult to detect or repair, leading to reduced reliability and shorter lifespan of these materials. The solution to such a problem lies in self-healing nanofibers.

What are self-healing nanofibers?

Self-healing is a relatively new perspective for advanced and responsive materials. Nanomaterials that can heal themselves, such as mimicking the healing of biological organisms, are known as self-healing nanomaterials.

The nanofibers in such materials automatically repair the damaged area immediately. These materials are used in a variety of applications in scientific fields, including engineering, military, power generation, dentistry, orthopedics, communications, construction, aerospace and automotive.

How are self-healing nanofibers manufactured?

Electrospinning is a unique process used to fabricate nanofibers using an electrostatic field. It is based on the principle of electrohydrodynamics.

In this process, nanofibers are produced by the acceleration of liquid jets with self-healing properties that are subject to coupled effects of an electric field on viscous liquids such as melts, dispersions and solutions. These liquid jets undergo stretching, evaporation and solidification processes, after which nanofibers can be collected.

Compared to other approaches to nanofiber processing, this technology is not only easy to use, but also relatively economical, due to its adaptability in manufacturing continuous nanofibers from a wide variety of polymers. There are several advantages to fabricating nanofibers using this technique, including competence in mass production, ease of combining materials, fiber functionality, and fine-tunable fiber properties.

Electrospinning methods have undergone significant development over the past two decades, allowing greater morphological control over the deposited nanofibers and improving fiber production and variety. During the last two decades, several electrospinning-derived models have been developed and patented, including electroblowing, multijet electrospinning, near-field electrospinning, melt electrospinning, bubble electrospinning, coaxial electrospinning and needleless electrospinning.

Recent research

In a recent study conducted in 2021, scientists were able to design a new composite hydrogel composed of polyaniline (PANI), polyacrylic acid (PAA), and 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNFs). These scientists studied several properties of this new composite, including sensing, self-healing, conductive and mechanical properties. This hydrogel showed an electrical conductivity of 3.95 S m-1tensile strength of 74.98 and elongation at break of 982%, as well as excellent self-healing properties without any irritation.

What are the applications of self-healing nanofibers in different industrial sectors?

Self-healing nanofibers have several potential applications in various industrial sectors, including aerospace, electronics, defense, textiles (protective clothing) and biomedical applications.

Space application:

The space is a very hostile place for construction materials because of the environmental conditions. Material damage can be caused by chemical, mechanical, thermal and UV radiation or combinations of these components. In addition, space debris in lower obits is also dangerous to satellites and spacecraft and can damage them. Therefore, it is imperative to develop self-healing systems that minimize damage before it leads to catastrophic failure.

NASA scientists have developed a self-healing materials system that can minimize the hypervelocity or ballistic effects such as micrometeoroids. This nanomaterial has the ability to self-heal within microseconds over a wide temperature range. This system has other applications such as aircraft MMOD shielding liners, pneumatic shielding, radiation shielding, and fuel reservoirs.

Electronic Application:

Several self-healing nanopolymers have been used to make electronics, such as supercapacitors, smart wearables, batteries and artificial muscles. New artificial skin-like electronics can sense humidity, temperature and pressure. This self-healing artificial skin is expected to be widely used in wearable devices and soft robotics, greatly reducing costs as these electronics can self-heal.

Defense Application:

Fiber-reinforced self-healing nanopolymers have diverse applications in the defense sector, including ground vehicles, tactical structures, aviation (helicopters and drones) and armor (vehicles and personal equipment). Repairability and maintainability are critical in the defense industry. Due to anti-ballistic, self-healing and lightweight properties, self-healing nanocomposites are ideal for defense applications such as protecting the fuel tank body against hypervelocity and ballistic damage.

Nanotechnology made intelligent uniforms for soldiers possible. Manufactured by a combination of nanostructures with micro and macro fibers, these self-healing suits provide a shield against chemicals, harmful biological agents, fragments from grenades and bullets.

Biomedical Application:

Recently, self-healing hydrogels have been applied in the biomedical field in drug delivery, cell culture and tissue engineering. Self-healing biological hydrogels are used in the treatment of brain injuries because of their adoptive physical, chemical and biological properties.

For example, collagen type I biohydrogels are known for their self-healing ability, injectability, non-cytotoxicity and biocompatibility, making them ideal for nerve tissue repair. Moreover, these self-healing scaffolds of biohydrogels are of great importance in neuroregeneration.

Read more: Agricultural applications of nanofibres.

References and further reading

Chaudhary, K., & Kandasubramanian, B. (2022). Self-healing nanofibers for technical applications. Research on Industrial and Engineering Chemistry, 61 (11), 3789-3816. https://doi.org/10.1021/acs.iecr.1c04602

Jiao, Y., Lu, Y., Lu, K., Yue, Y., Xu, X., Xiao, H., … & Han, J. (2021). Highly stretchable and self-healing cellulose nanofiber-mediated conductive hydrogel for stretch sensing application. Journal of Colloid and Interface Science, 597, 171-181. https://doi.org/10.1016/j.jcis.2021.04.001

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