Flexible and Stretchable Hydrogel-based Composites using Ag Coated Hollow Glass Microspheres and Polypyrrole Nanotube Supported Ferroferric Oxide for Electromagnetic Interference Shielding

Developing flexible and efficient electromagnetic interference (EMI) shielding composites has become an unavoidable trend in response to increasingly sophisticated application scenarios of electronic devices. In this context, organic hydrogel-based composites with excellent EMI shielding effectiveness (EMI SE) are assembled by a sol-gel strategy and a layer-by-layer casting process. Due to the combined effect of the multi-interface conductive network composed of highly conductive Ag-coated hollow glass microspheres (HGM@Ag) and the asymmetric structure constituted by the tremendous conductivity difference between HGM@Ag and polypyrrole nanotube-supported ferroferric oxide (PNT@Fe3O4), the resulting composite exhibits a maximum EMI SE of 109.5 dB, while reflection shielding effectiveness (SER) is only 3.7 dB. Moreover, after undergoing numerous tensile cycles and water loss-soak cycles, the prepared composite could be restored to 97 and 95.8% of its original EMI shielding performance, respectively. The superior shielding and mechanical properties could be attributed to the conductive loss of HGM@Ag combined with the magnetic loss of PNT@Fe3O4, as well as the highly cross-linked network formed by the hydrogen bond between poly(vinyl alcohol) (PVA) and polyethylene glycol (PEG) which is further enhanced by dimethyl sulfoxide (DMSO) and H2O binary solvent system. Therefore, this study provides a perspective for developing flexible, stretchable, and multifunctional conductive hydrogel composites to achieve high-performance wearable EMI shielding materials.