# Electromagnetic Radiation Shielding Using Carbon Nanotube and Nanoparticle Composites
## 4 CNT-Based Materials for Electromagnetic Interference (EMI) Shielding
Similarly, the integration of silver (Ag) and magnetic carbon nanotubes (mCNTs) onto PP fabrics marks a significant leap in flexible EMI shielding. These lightweight coatings, applied through a simple spray deposition technique, provide reliable shielding for flexible electronics. Incorporating magnetic nanoparticles and metal porphyrins shows promise in enhancing electromagnetic-wave-absorption capabilities, driving the development of advanced EM-shielding materials. Investigations into MXenes and carbon-based materials also reveal their potential in advancing EM-shielding and energy-storage applications. These innovations expand the use of CNTs beyond traditional metal-based shielding materials, offering a versatile, corrosion-resistant solution with broad industrial potential. This analysis highlights the impact of these materials on modern electronics, enabling future advancements. [PERSON] et al. [65] highlight the growing concern about electromagnetic radiation pollution due to the rise of wireless communication and electronic devices, which pose risks to both devices and human health. This has led to an increased demand for efficient EMI-shielding materials. While traditional metals provide satisfactory EMI-shielding effectiveness (SE), they suffer from issues such as corrosion, high density, and lack of flexibility. Conductive polymeric composites are promising alternatives, offering advantages like processability, elasticity, low cost, corrosion resistance, and lightweight properties. Since polymers are inherently nonmagnetic and insulative, they require conductive fillers to establish effective EMI-shielding networks. Various fillers, including metal powders, nanowires, graphene, CNTs, carbon nanofibers, and conductive ceramics, have been investigated to enhance EMI-shielding performance. Hybrids like graphene-carbon nanotubes and MXene-based composites show significant improvements in EMI-shielding effectiveness. Different structural architectures, such as multilayered, segregated, gradient, and foam structures, optimize the EMI-shielding performance. Foam structures enhance EMI shielding through high porosity, while layer-by-layer sandwich structures yield lightweight, and flexible EMI-shielding materials. [PERSON] et al. also introduced a novel approach for fabricating flexible multilayered films for EMI shielding. These films consist of alternating layers of nanofibrillated cellulose (NFC)/Fe\({}_{3}\)O\({}_{4}\) and CNT/polyethylene oxide (PEO), offering excellent electrical and thermal conductivity and outstanding EMI-shielding effectiveness. The inclusion of magnetic Fe\({}_{3}\)O\({}_{4}\) particles further enhances EMI shielding. These films have improved toughness compared to pure NFC films, making them suitable for applications in the communication industry, portable electronics, and robot joints. The materials used in the study by [PERSON] et al. include NFC, ferro-ferric oxide (Fe\({}_{3}\)O\({}_{4}\)), MWCNT, polyethylene oxide (PEO), and deionized water. The films were fabricated through a layer-by-layer self-assembly process under alternating vacuum filtration (AVF). Characterization techniques included scanning electron microscopy (SEM), energy-dispersive spectrum (EDS) mappings, X-ray diffractometer (XRD) analysis, and an investigation of EMI- SE using a vector network analyzer (VNA). Mechanical properties were tested using a universal testing machine. The films demonstrated high electrical conductivity and outstanding EMI-shielding properties, surpassing single CNT/PEO films. Theoretical calculations suggested that both absorption and reflection mechanisms contributed to EMI shielding, with a dominant reflection mechanism observed. The films had high in-plane thermal conductivity and improved mechanical properties with an increasing layer number, making them suitable for flexible and wearable electronic devices. An EMI-shielding application showcased the films' effectiveness in blocking electromagnetic wave transmission.