Asymmetric Three-Dimensional Porous-Planar Integrated Structure of Elastic Melamine Foam Composites with One Side Absorbing and One Side Reflecting Electromagnetic Shielding Properties

Asymmetric structural design and reduction of secondary contamination have been at the forefront of the development of electromagnetic shielding composites. Herein, the melamine foam@ferric oxide/cellulose nanofibers@carbon nanotube/polydimethylsiloxane/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (MF@Fe3O4/CNF@CNT/PDMS/PEDOT:PSS) (MC2PP) composites with an asymmetric three-dimensional porous-planar integrated structure are prepared by a solvothermal reaction, infiltration, and coating. A PDMS-encapsulated MF@Fe3O4/CNF@CNT porous composite is designed as an absorbing layer for absorbing electromagnetic waves (EMWs). The conductive polymer PEDOT:PSS, coated on the upper surface of the MF@Fe3O4/CNF@CNT/PDMS composite, is designed as a reflective layer. The MC2PP-2.4 composite obtains an average SET of 38.81 dB and an absorption coefficient (A) value of 0.654 at the X-band when the EMWs are incident from the MF@Fe3O4/CNF@CNT/PDMS side (M-side, porous absorber layer). When the EMWs are incident from the PEDOT:PSS side (P-side, planar reflecting layer), the MC2PP composite obtains an average SET of 39.00 dB and a reflection coefficient (R) of 0.964. The asymmetric structural design, along with conductive losses, magnetic losses, and interface polarization, contributes to the electromagnetic shielding performance that can be absorbed on one side and reflected on the other. More importantly, the elastic melamine foam composites are simple to prepare, reliable in process, stable in performance, and a unique scalable composite material, which have a broad application prospect in the field of electromagnetic interference shielding.