Ultrathin-flexible multifunctional MXene composite hydrogels with good mechanical properties-high strain sensitivity and ultra-broadband EMI shielding performances

Conductive hydrogels show excellent application potential in flexible and stretchable electromagnetic interference (EMI) shielding materials due to their water-rich porous structure and tissue-like mechanical properties. However, integrating multiple functions into EMI shielding materials remains challenging, including ultra-broadband EMI shielding, mechanical properties, strain sensitivity, flexibility, etc., with high performance. Here, through a straightforward and scalable combination of ultrasound-assisted dispersion and thermal polymerization, we have successfully synthesized the MXene/PE-CS composite hydrogels composed of acrylic acid (AA), 2-(Dimethylamino) ethyl methacrylate (DMAEMA), and chitosan (CS). It exhibits more comprehensive and excellent functionalities including high stretchability (0.47 MPa, 747 %), strain sensitivity (11.2), ultralow thickness (0.5–2.0 mm), good adhesion (0.13 MPa), and flexibility. More importantly, it achieves excellent shielding performance of more than 99.99 % in ultra-broadband (X-band, Ka-band, Ku-band, and THz-band) under ultralow thickness (0.5–2 mm) and MXene (transition metal carbides/nitrides) content (0.46 wt%), and the shielding properties can be dynamically controlled through MXene content, PE content and hydrogel thickness. Even after repeated stretching, bending, and long-term water evaporation, it still exhibits stable and high-performance EMI shielding performance. Our MXene/PE-CS composite hydrogels exhibit potential applications in ultra-broadband shielding for new generation flexible wearable electronic devices.