Conductive Composite\nInks Comprised of Waterborne\nPolyurethane, Silver Nanosheets, and Heat-Treated MXene Nanosheets\nfor Electromagnetic Shielding and Thermal Management

As\nwearable and flexible electronic devices continue\nto miniaturize\nand operate at higher frequencies, there is an urgent demand for polymer\nfilms that offer a high electromagnetic interference (EMI) shielding\nefficiency and effective thermal management capabilities, particularly\nunder extreme environmental conditions. Conductive inks are extensively\nutilized in polymeric electromagnetic interference shielding coatings.\nHowever, the extensive utilization of organic solvents can lead to\nenvironmental pollution. Herein, we proposed a multifunctional conductive\ncomposite ink comprising waterborne polyurethane (WPU), silver nanosheets\n(AgNS) and heat-treated MXene, using deionized water as solvent. Inspired\nby the advantage of the unique “brick-mortar” layered\nstructure, we fabricated a multifunctional flexible composite film\nwith large size, high electrical conductivity, and good mechanical\nflexibility by blade coating, which has scalable manufacturing prospects\nfor industrialization. The resultant films achieve a remarkable EMI\nSE of 87.3 dB at only 78 μm thickness and impressive mechanical\nfastness and chemical durability to various organic solvents. Meanwhile,\nthe resultant composites also present a desirable Joule heating temperature\n(117 °C) and anisotropic thermal conductivity due to the compact\nand highly aligned morphology. In summary, our simple preparation\ntechnology and excellent comprehensive performance of composite inks\nhave great potential in advanced thermal management and wearable electromagnetic\nprotection devices.