Heterogeneous asymmetric double-layer composite with ultra-low reflection for electromagnetic shielding

In this work, a heterogeneous asymmetric double-layer composite (HADC) consisting of an absorbing layer Fe3O4@reduced graphene oxide (rGO)/waterborne polyurethane (WPU) and a reflecting layer Ni-Co-P@FC (Ni-Co-P coated filter cotton (FC)/PANI@PDMS (polyaniline (PANI) mixed in polydimethylsiloxane (PDMS)) was designed and prepared using a simple chemical plating method and stirred foaming process. In which, the upper Fe3O4@rGO/WPU foam utilizes the combined effects of the porous internal structure and Fe3O4@rGO to achieve superior impedance matching and electromagnetic waves (EMW) absorption performance, while the Ni-Co-P dense conductive network formed by chemical plating process within the bottom layer ensures superior electromagnetic shielding effectiveness (EMI SE). The advantage of heterogeneous asymmetric structure combined with the reasonable distribution of electromagnetic two-component fillers and under the effects of multiple electromagnetic loss mechanisms, the composite structure perfectly overcomes the contradiction between efficient shielding and high absorption. Ultimately, the HADC exhibits a high EMI SE of 36.6 dB and absorption coefficients (A) value of 0.94, showing ultra-low reflection efficiency, which is better than most current shielding materials moreover, the preparation process is simple, with the characteristics of low cost and environmentally friendly. Therefore, this work provides a simple and feasible new idea for the preparation of lightweight, efficient and ultra-low reflection EMI shielding composite structures, which broadens the application of porous structures in the field of electromagnetic shielding.