Absorption-dominated double-layered electromagnetic interference shielding polymer-based nanocomposites: Optimal design and manufacturing

Double-layered electromagnetic interference (EMI) shielding composites having a gradient structure to achieve an efficient EMI shielding effectiveness (SE) with a low electromagnetic wave reflectivity (R) would be highly desired for engineering applications to control secondary electromagnetic pollution. However, it is still challenging to optimize their performance and structure efficiently. In this work, theoretical calculations were conducted on the prepared double-layer shielding polymer composite material using an improved normalized input impedance (NII) method to verify and optimize the structural composition and R-value of the composite material. The R-value of the composite can be calculated iteratively based on the conductivity and electromagnetic parameters of each material layer, and in this way the optimal structural composition to achieve the lowest R-value can be well predicted. Thus, the optimal structural composition to achieve the lowest R value can be well predicted from the theoretical calculation. Suggested by the theoretical calculation, the double-layered waterborne polyacrylate/polydopamine modified reduced graphene oxide/Cu@Ag (WPA/rGO@PDA/Cu@Ag) composite has achieved broadband low-reflectivity. The R values of the resultant WPA/rGO@PDA-20 wt%/Cu@Ag-1.448 mm composite are <0.5 over 8.3-12.4 GHz, implying its broadband low reflection performance while possessing a high EMI shielding effectiveness beyond 44.3 dB. The modified NII method is promising for advancing the practical production and engineering application of multilayered absorption-dominated EMI shielding composites.