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Page 18 of 25 Liu et al. Soft Sci. 2025, 5, 7 https://dx.doi.org/10.20517/ss.2024.69

loss from interfacial coupling effects and superior impedance matching from multilayered porous materials
[105]
[Figure 9A]. It also had a secondary recovery, multi-absorption, and heat-insulating abilities . ZIF-67/
MXene/CNF carbon aerogel was fabricated by freeze-drying and carbonization. The porous structure and
the synergy of magnetic/electric loss facilitated the impedance matching. Heterointerfaces induced
interfacial and dipole polarization [Figure 9B]. The aerogel had an EMI SE of 86.7 dB and an absorption
[103]
coefficient of 0.72 . Vacuum-assisted filtration was used to prepare a six-layered film with alternating
CoFe O @MXene/CNF layers and AgNWs/CNF layers. Due to the magnetic/electric coupling, multi-
2
4
scattering and absorption [Figure 9C], the film at 0.1 mm had an EMI SE of 87.8 dB with a reflection of
5.6 dB. After being attacked chemically and physically, it retained 97% of its EMI SE. It also had a tensile
strength of 183.2 MPa, an in-plane TC of 6.875 W/(m center dot K) and a Joule heating performance of over
[15]
90 °C at 3.0 V in 20 s. The inferior through-plane TC provided an infrared stealth performance . Cotton-
derived flexible carbon fiber (CF)/rGO was prepared by electrostatic self-assembly, and then NiCo-layered
double hydroxides (LDH) were arranged on CF/rGO to form a core-sheath structure composite. The
composite at 2.5 mm had an RL of -60.9 dB at 10.3 GHz and an EBA of 6.1 GHz with 20 wt% filling. The
carbonized CF contains heteroatoms, enhancing the dielectric loss caused by polarization. rGO facilitated
the conductive loss. The voids created by the stacked LDH induced the reflection and scattering of EMW
and optimized the impedance [Figure 9D] .
[106]

PI
PI has thermal stability and high mechanical properties, multi-reflection and scattering, and EM absorption
can be facilitated by PI composite foam. A strategy to increase the EM attenuation of composite foam is to
add conductive and/or magnetic fillers to create a conductive network inside PI foams, as pure PI displays
weak EM absorption due to its intrinsic low dielectric constant [1,107] .

A MXene@PI foam was prepared by directional freezing, freeze-drying, thermal imidization, and dip-
coating. The cation-π interaction enhanced the PI framework and the interfacial interaction. The structure
of the foam was tubular in the vertical freezing direction and honeycomb-like in the parallel freezing
direction. With the same MXene loading, the EMI SE of the foam was 62.7 dB in the vertical direction,
158.0% greater than that in the parallel direction, and 109.7% greater than that of the isotropic foam . A
[1]
Ti C T MXene/PI nanofibrous aerogel was fabricated via freeze-drying and thermal imidization. The
3 2 x
porous 3D network improved multi-reflections and scattering and offered good matched impedance. The
heterostructure enhanced the interfacial polarization, whereas the functional groups and defects on MXene
caused dipole polarization. The aerogel exhibited an RLmin of-37.9 dB and an EAB of 3.3 GHz. It also had a
low TC of 35.2 W·m ·K and high compression properties .
-1
[107]
-1
Polysiloxane and its derivatives
A multilayered composite was prepared using liquid polycarbosiloxane-derived SiOC, ZrO /SiO , and nano
2
2
ZrB by hot press curing and pyrolysis. The composite showed an EAB of 4.2 GHz at 2.9 mm and an RLmin
2
of -59.34 dB because of the excellent impedance matching and EMW loss caused by the conductive loss and
multilayer interfacial polarization. It also had thermal insulation, oxidation resistance, and a notable
[67]
decrease in radar cross-section . A Co-SiCN ceramic was prepared by the mixing of polysilazane and ZIF-
67 and then pyrolysis. To optimize their impedance matching, the ZIF-67 encouraged the production of
dielectric loss phases, such as CoSi, SiC, and free C. An EAB of 3.0 GHz at 1.05 mm and an RLmin of
-46.4 dB at 6 GHz were attained due to the impedance matching and heterointerface polarization . A
[108]
silicon oxycarbonitride (SiOCN) ceramic bowl was prepared from a hollow polysilsesquioxane by pyrolysis.
Multi-reflections/scattering and impedance matching were enhanced by the bowl structure. Dipolar and
interfacial polarization sites were generated by the hetero-nanodomains between the SiOCN and free C
[109]
phase. The ceramic bowl exhibited an RLmin of -52.93 dB at 2.3 mm and an EAB of 3.88 GHz at 1.6 mm .