Enhanced EMI shielding and mechanical stability via deformable MXene-rNGO conductive networks in superelastic PDMS composite

Abstract

Traditional conductive composites are often vulnerable during the deformation process, leading to decrease electromagnetic interference (EMI) shielding efficiency (SE). In this work, a deformable conductive network was innovatively constructed by assembling multiple flexible interfaces to stabilize the EMI SE. The reduced N-doped graphene oxide (rNGO) and exfoliated MXene with different surface charges were successively coated on the surface of thermal expansion microspheres (TEMs, diameter about 11 μm) to construct a conductive shell with flexible splicing interfaces. Further, the assembled functional microspheres (TM@rNG-MX) were hybridized with poly(dimethysiloxane) (PDMS) and then thermally expanded to obtain the multifunctional PDMS/TM@rNG-MX composite. The dynamic connection between rNGO and MXene on the expanded TEMs (diameter about 29 μm) was efficient for establishing 3D deformable conductive networks, which remained intact even after significantly deforming the PDMS composite (strain of 80 %). Surprisingly, the EMI SE (X band) of PDMS/TM@rNG-MX reached 48.8 dB under a low filling content of rNGO and MXene (2.6 wt%), which remained stable after being stretched. In addition, PDMS/TM@rNG-MX had excellent superelasticity and fatigue resistance properties, and the energy loss coefficient reached 72.03 % at 80 % compression, indicating the extraordinary ability on absorbing impact energy. Therefore, this study presents an innovative approach to effectively enhance the mechanical stabilities and EMI shielding performance of flexible and conductive composites.