Nanoparticles made of carbon have attracted a lot of interest recently, largely due to their potential to improve the transport characteristics of polymer nanocomposites and support electrically conductive polymer use in more demanding applications. As such, shielding electronic devices from the electromagnetic radiation produced by other electronic components or products, also known as electromagnetic interference (EMI) shielding, has received special attention.

What is EMI shielding?

With EMI shielding, a device or circuit is protected from interference by employing magnetic or electrically conductive enclosures. The necessity to prevent electromagnetic signal interference grows in importance as the number of electronic products that depend on these signals continues to rise. There are a wide variety of uses for EMI shielding components, including separating electrical and electronic products, and providing radio frequency (RF) shielding defense against potential interferences in laboratory and medical apparatus.

What are EMI shielding materials made of?

Given the importance of electrical conductivity to EMI shielding, metal sheets are a popular choice when it comes to EMI shielding materials. Nickel or aluminum alloys, copper, foams or screens made of steel, are also frequently used because of their dielectric constant and high electrical conductivity. Even so, metal-based shielding systems exhibit major downsides that restrict their applications, including poor resistance to corrosion, high density, costly processing and an EMI shielding method dependent on reflection. These factors hinder their usage in areas where EMI absorption is prominent, for example, in stealth technology, and can impair their performance or even destroy other electronic components or circuits.

How to overcome drawbacks of using metal-based EMI shielding materials

Though conductive polymers may offer a solution to some of these issues, they can often deliver poor mechanical performance and poor thermal stability, which translate to a restricted service temperature or excessive manufacturing and material costs. Because of this, polymer composites comprising carbon-based nanoparticles that are conductive in nature have emerged as a promising alternative. This option combines in a single material the benefits of polymers with those provided by the incorporation of carbon-based nanoparticles. These beneficial properties include good mechanical performance, thermal stability and electrical conductivity.

Research has demonstrated that polymer composites containing carbon nanoparticles can support a shift in the principal shielding method against electromagnetic radiation under certain (micro)structural circumstances. They can offer multiple reflection or pure absorption methods for EMI shielding. Foams made from these polymer nanocomposites are one such example.

Improvements have been made in methods for combining carbon-based nanoparticles with polymers, as well as in the ability to regulate the attributes such as geometry and aspect ratio and crystalline characteristics of the synthesized nanoparticles.

What are the advantages of nanocomposites for EMI shielding?

In addition to eliminating the usual drawbacks of metals (high processing expense, high density and poor corrosion resistance), carbon-based polymer nanocomposites allow the combination of many multifunctional features, including the potential for tunable EMI shielding properties. All of this will be affected by factors besides than electrical conductivity, such as the technique of shielding, the probable orientation of materials, and the resulting directionality of protection, each of which can undergo transformations in the course of compounding and processing with far less difficulty than metals.

Additionally, polymer nanocomposites may be studied at several scales, beginning with the microstructural features of the matrix, because of their multiphase nature. For example, in foams, this can even include the likely formation of cellular structure, uses of nanoparticles with varying aspect ratios and geometries, or nanoparticles combined with other microparticles. The increased processing flexibility of polymer nanocomposites allows for an even wider range of microstructural options, and hence, final property profiles. With these factors in mind, it's easy to see why carbon-based polymer nanocomposites are finding widespread usage in cutting-edge industries like electronics and aerospace.

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Conclusion

Nanocomposites based on carbon for EMI shielding materials have lately garnered a lot of attention due to their potential to enhance the transport properties of polymer nanocomposites, hence allowing more extensive usage of electrically conductive polymers. Conductive carbon-based nanoparticle-containing polymer composites have recently been proposed as a potential replacement to the standard polymer composites and metals for EMI shielding materials. In spite of this, there is a significant scientific and technical drive to learn more about these complicated multiphase materials and find new applications for them.