Synergistic EMI Shielding: The Role of Nanoparticle Size and Alternating Bi‐Layer Coatings in Hybrid Fabrics

Abstract This study presents a hybrid knitted fabric engineered for high‐performance electromagnetic interference shielding effectiveness (EMI SE), achieving a maximum shielding effectiveness of 59.4 dB. The functionalized fabric is made from copper‐cotton core‐spun yarn with alternating bi‐layer of silver nanoparticles (AgNPs), MXene to enhance both conductivity and reflection/absorption. By employing a reactive in situ synthesis process, AgNPs are successfully synthesized directly onto the fabric, achieving particle sizes that range from 15 to 38 nm. Notably, smaller nanoparticles showed improved shielding performance by 7 dB, highlighting the important role of particle size in enhancing EMI shielding effectiveness. In addition, increasing the number of coating layers enhances the shielding effectiveness. In order to improve the durability of the fabric, (3‐Aminopropyl)triethoxysilane (APTES) treatment is performed, which contributed to the preservation of stable EMI shielding properties, even after 90 min of washing. Beyond EMI shielding performance, the APTES‐treated fabrics demonstrate good air permeability and moisture vapor transmission rates, ensuring they are breathable and comfortable, making them potential candidates for wearable applications where EMI exposure is a concern.