Highly stretchable liquid metal/poly(urethane-urea) composite with self-healing ability for electromagnetic interference shielding

Stretchable electromagnetic interference (EMI) shielding materials with self-healing ability are in high demand to guarantee the service reliability in the next-generation flexible electronic devices. However, it still remains challenging to yield highly stretchable EMI shielding materials with self-healing ability at room temperature. Herein, room-temperature self-healing poly(urethane-urea) (PUU) is first synthesized by designing disulfide and ammonium ester bonds, and then soft liquid metal (LM) is used as a conductive filler to yield highly stretchable LM/PUU composites with room-temperature self-healing ability. The LM/PUU composite with 40 vol% LM exhibits a high EMI shielding effectiveness (EMI SE) of 34.1 dB at a tiny thickness of 0.3 mm, and the EMI SE increases slightly to 36.3 dB even at 100 % strain, indicating excellent stretching stability. The self-healing efficiency is as high as 94.2 % for the LM/PUU composites after being treated at room temperature for 10 min. It is also demonstrated that the LM/PUU composites possess good thermal conductivity and Joule heating performance. This study proposes a new approach to developing highly stretchable EMI shielding materials with selfhealing ability for advanced EMI shielding applications in the area of flexible and durable electronic devices.