Preparation of Ultralong AgNWs/PU Composite Foam for Outstanding Electromagnetic Interference Shielding, Joule Heating, and Human Motion Detection

With the booming development of communication technology and electronic devices, increasingly complex real-world scenarios propose higher demands on electromagnetic interference (EMI) shielding materials. Wearable EMI shielding materials with Joule heating capability and human motion detection can effectively promote benign functioning of the human body and protect sensitive electronic devices in cold and harsh environments. In this paper, silver nanowires (AgNWs)/polyurethane (PU) composite foams with multicellular structures were prepared by a simple dip-drying method. Benefiting from the high conductivity (10,417 S m –1 ) of the ultralong AgNW network and the interfacial polarization between the silver nanoparticles and the AgNWs, the composite foams have a high EMI shielding performance dominated by microwave absorption. The EMI shielding effectiveness (SE) and specific EMI shielding effectiveness (SSE/ t ) of the composite foam in the X-band (8.2–12.4 GHz) reached 94.96 dB and 9,169.8 dB cm 2 g –1, respectively. The electromagnetic shielding effectiveness is up to 99.99999997%. Meanwhile, at an external voltage of 0.75 V, the surface saturation temperature of the IAgNWs –5 /PU composite foam rapidly increased from room temperature to 125.6 °C and remained steady. Furthermore, the IAgNWs –5 /PU composite foam can be used as a multifunctional sensing device for monitoring human motion signals based on the good resilience of the PU foam and the stability of the AgNW conductive network. These superior properties make the AgNWs/PU composite foam have great potential applications in military equipment, aerospace, and wearable electronic devices.