Lightweight and Robust Carbon Nanotube/Polyimide Foam for Efficient and Heat-Resistant Electromagnetic Interference Shielding and Microwave Absorption

Abstract

Excellent electromagnetic interference (EMI) shielding ability, light weight, and good heat resistance are highly required for practical applications of EMI shielding materials, such as in areas of aerospace, aircraft, and automobiles. Herein, a lightweight and robust carbon nanotube (CNT)/polyimide (PI) foam was developed for efficient and heat-resistant EMI shielding. Thanks to poly­(vinyl pyrrolidone) (PVP) as a surfactant that not only promotes the uniform dispersion of CNTs to form perfect CNT conductive networks but also can be removed in situ during the polymerization process, the density of resultant CNT/PI foam is only 32.1 mg·cm–3, and the EMI shielding effectiveness (EMI SE) is up to 41.1 dB, which represents one of the highest EMI SE values compared to previously reported polymer-based foams. The CNT/PI foam also achieves the absorption coefficient (A) of up to 82.3%, which is very impressive in CNT/polymer foams at comparable EMI SE levels. The PI matrix endows the foam with excellent heat resistance. The as-prepared CNT/PI foam presents a higher EMI SE than 35 dB even after being subjected to the flame of an alcohol burner. Moreover, the compressive strength and compressive modulus are up to 240.9 and 323.9 kPa. These results indicate its certain application potential in the harsh requirement of aeronautics and aerospace industries as a highly efficient and lightweight EMI shielding material.

Super-elasticity at 4 K of covalently crosslinked polyimide aerogels with negative Poisson’s ratio

“…Generally, freeze-casting techniques based on water-soluble PI precursors of poly (amic acid) ammonium salt (PAAS) are widely applied in the fabrication of elastic PI aerogels 23 , 24 . Based on this strategy, various elastic PI aerogels composited with CNTs 25 , 26 , graphene 27 , 28 , silica 29 , MXene 30 , 31 , and nanofibers 32 , 33 have been produced, endowing PI aerogels with such promising applications as electromagnetic shielding, oil-water separation, pressure sensors, etc. Unfortunately, the thermal imidization after freeze-drying in the above strategy inevitably causes large shrinkage up to 40%, greatly impairing the compressibility of elastic PI aerogels 34 .…”

The influence of the transparent layer thickness on the absorption capacity of epoxy/carbon nanotube buckypaper at X‐band

“…14 Absorption losses may also have benefited from the impedance mismatch between BP and epoxy resin, which results in the absorption of EM waves trapped in the Epoxy/BP interfaces. 6,44 Also, a portion of the transmitted waves through the interface area may have been trapped between the two conductive plates, thus resulting in increased absorption capacity.…”

Tailoring specific properties of polymer-based composites by using graphene and its associated compounds

“…Wang et al [27] adopted carbon nanotube, as a conductive filler to mix with Polyimide foam to for a composite to isolate EMI transmission. The nanotubes formed a conductive path in the foam network.…”