# Electromagnetic Radiation Shielding Using Carbon Nanotube and Nanoparticle Composites
## 4 CNT-Based Materials for Electromagnetic Interference (EMI) Shielding
This work highlights the potential of capillarity-assisted assembly techniques in developing effective and practical EMI-shielding fabrics. [PERSON] et al. [56] conducted a study on the shielding properties of free-standing polymer/MWCNT composite thin films, contributing valuable insights into the potential applications of CNT films for EMI shielding. Their extensive investigation included both thermal conductivity and EMI-shielding effectiveness, providing a holistic understanding of the composite thin films' properties. The use of a simple casting method for film fabrication enhanced the practicality of these composites for real-world applications. However, the researchers acknowledged potential variations in film thickness during casting and emphasized the need for further characterization techniques to fully elucidate the microstructure and interfacial properties of the composite films. Their findings suggest that these films exhibit tunable thermal conductivity and excellent EMI-shielding effectiveness due to the formation of a well-connected MWCNT network within the polymer matrix. The study emphasizes the scalability of the production methods and the multifunctionality of the composite films, highlighting their potential for customized thermal management and EMI-shielding solutions in industries such as aerospace, automotive, and telecommunications. The ability to tailor the thermal and shielding properties of these films makes them promising candidates for a wide range of advanced technological applications. [PERSON] et al. [58] demonstrated that coating knitted cotton textile substrates with multi-walled carbon nanotubes and graphene nanoplatelets (GNPs) through the Dip-Pad-Dry process resulted in higher EMI shielding. They concluded that the thickness and electrical properties of the EMI shield correlate with the shielding process, particularly absorption. In 2011, [PERSON], [PERSON], et al. [59] investigated the EMI-shielding effectiveness of CNT macro-films. They showed that a 4 \(\upmu\)m-thick CNT macro-film achieved EMI shielding effectiveness of 61 to 67 dB, indicating that CNT macro-films can be used for EMI-shielding materials. Furthermore, adding iron particles to the CNT bundles can further enhance EMI-shielding effectiveness. Adding metal ions to the ends of CNTs in a film can enhance radiation attenuation [60]. According to [PERSON], copper ions bind to CNTs more effectively than other metal ions, with lead being the second-best. [PERSON] [61] found that copper, when bound to borate zinc-fluoride glasses, increases radiation protection. However, more research is needed to understand how different metal ions affect the attenuation coefficient of CNT film material. Polymer shielding has also been extensively investigated as a method of radiation attenuation. Polymers are cheap, flexible, and durable. [PERSON] and colleagues [62] showed that incorporating different elements into a polymer matrix increases radiation attenuation. Combining polymers with metal particles and CNTs can improve the shielding properties of films. For example, polymers with fillers such as bismuth oxide can provide customizable attenuation, with elements of higher atomic numbers typically used as fillers. Different studies by [PERSON] et al., [PERSON] et al., [PERSON] et al., and [PERSON] et al. [63; 64; 65; 66] have established that CNT materials can be tailored to address specific challenges in radiation attenuation and EMI shielding. Each hybrid CNT material possesses unique properties, ranging from high thermal conductivity and EMI-shielding effectiveness to flexibility and lightweight construction. In today's electronics landscape, where integration and miniaturization are key, hybrid nanofibrillated cellulose/Fe\({}_{3}\)O\({}_{4}\)+CNT/polyethylene oxide (NFC/Fe\({}_{3}\)O\({}_{4}\)+CNT/PEO) films have gained attention. These films boast flexibility and toughness due to their unique multilayered structures, offering robust radiation shielding and effective heat dissipation.