Flexible Polyimide Foams Coated with Graphene Nanoplatelets/Fe₃O₄ for Absorption-Dominated Electromagnetic Interference Shielding, Broad-Band Microwave Absorption, and Sensor Applications

Abstract

With the rapid development of 5G communication technologies, the high-performance electromagnetic interference (EMI) shielding materials with less secondary reflection for electronic devices have become an urgent demand in recent years. In this study, flexible opencell polyimide (PI) foams containing graphene nanoplatelets (GN)/Fe 3 O 4 coatings for absorption-dominated EMI shielding were fabricated. The result shows that the EMI shielding efficient (EMI SE) of composite foam PI/GN/ Fe 3 O 4 (PF/GN/Fe 3 O 4 ) can achieve 60.6 dB with a thickness of 6.0 mm along with an absorption coefficient (A) of 0.4−0.6, indicating excellent EMI shielding and a low reflection property. Furthermore, the optimal reflection loss (R L ) of PF/GN/Fe 3 O 4 with a low GN loading can be up to −35 dB at 5.0 mm and less than or equal to −10 dB in the whole X-band with a thickness of ≥4.5 mm. In addition, the prepared composite foam PI/GN (PF/GN) exhibits good electrical conductivity of 2.5 × 10 3 S/m and sensing stability. Notably, this research systematically studied the application performance of the composite foam in EMI shielding, electromagnetic wave (EW) absorption, and sensing monitoring. The prepared composite foam can be applied as "Green" EMI shielding materials for flexible electronic devices due to the remarkable EW absorption properties.

Thin, Flexible, and High-Strength Graphene Films Modified with CoFe2O4 Nanoparticle–Carbon Nanotubes Composites for Electromagnetic Interference Shielding

“…Table compares the EMI SE of some recently reported EMI shielding materials to those of our films. Evidently, our CFO–CNTs/RGO p film exhibits a superior EMI shielding performance owing to its high EMI SE at a low thickness. ,,− …”

Advances in Graphene–Polymer Nanocomposite Foams for Electromagnetic Interference Shielding

“…Li and coworkers prepared a PI open-cell foam with pyromellitic diester and catalysts as component A and polyphenylene isocyanate as component B by a free-foaming method [52]. Apart from the different foaming means, the graphene nanoplatelets and Fe 3 O 4 nanoparticles were both adsorbed onto the PI foam by dip coating.…”