Ti3C2Tx MXene/carbon nanotubes/waterborne polyurethane based composite ink for electromagnetic interference shielding and sheet heater applications

Wearable and flexible electronic devices have attracted much attention in recent decades due to their novel functionalities which can be applied in diverse fields such as identification of emergency, health monitoring, safety, and protection. For these devices to work precisely, they need a protective layer to prevent electromagnetic interference (EMI) and harsh environment. Therefore, developing multifunctional materials that can shield EMI and have thermal management functions has become essential. Herein, we propose a multifunctional conductive composite ink that can be applied to fabricate EMI shielding and sheet heater applications. The composite ink, which is eco-friendly, is a mixture of carbon nanotubes (CNTs) and heat-treated Ti3C2Tx MXene in waterborne polyurethane (WPU) matrix. Using the doctor blade printing method, we fabricated composite films with large size, high electrical conductivity, and good mechanical flexibility. The composite films with a thickness from 20 to 200 µm provided a remarkable EMI shielding performance from 20 dB to 70 dB in overall X-band and Ka-band. The excellent Joule heating performance and heat dissipation of the composite films were also demonstrated through practical sheet heaters and thermal interface materials (TIM). We believe that our composite ink could be a practical approach to delivering superior EMI shielding and thermal management performance in printed wearable electronics applications.