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Page 6 of 25 Liu et al. Soft Sci. 2025, 5, 7 https://dx.doi.org/10.20517/ss.2024.69

exhibits high permittivity, often acting as a dielectric component to synthesize multi-component EMW
absorbing composites [3,80] .

For example, MXene/PANI composites were fabricated via electrostatic self-assembly. The PANI bridged
the MXene to construct a 3D structure that prolongs the EMW transmission path, and balanced the
impedance matching of MXene. The dipole and interfacial polarization provided efficient EMW
attenuation. When the thickness of the composite was 2.3 mm, the EAB reached 8.64 GHz, while the
composite containing 10 wt% PANI had a reflection loss (RL) of -60.6 dB and an EAB of 6.0 GHz . In
[55]
another study, a PANI-modified Co/N-doped C (Co-NC@PANI) with a sea urchin-like structure was
prepared, and then it was incorporated into an MXene-based gel by freeze-drying. The Co-NC@PANI
tuned the dielectric constant of MXene, introduced a magnetic loss, and optimized interfacial polarization
and impedance matching. The gelatin optimized the conductive transmission path [Figure 2A]. The RL and
EAB of the aerogel at 1.8 mm reached -62.4 dB and 6.56 GHz, respectively . An Au@MXene/cellulose
[31]
nanocrystal/dodecylbenzenesulfonic acid doped PANI (AMCP) film was fabricated via vacuum-assisted
filtration. Due to the heterointerface engineering, the film had an EMI SE of 67.9 dB. It achieved 100 °C in
5 min by an infrared lamp, and maintained stable photothermal conversion. It was also endowed with
thermal stealth capability due to the gaps between the layers [Figure 2B] .
[73]

A Fe O /PANI composite was fabricated by hydrothermal reaction and chemical oxidative polymerization.
4
3
The hollow Fe O and PANI enhance the interfacial polarization, multi-reflection and scattering loss
4
3
[Figure 3A]. The composite at 1.84 mm with a heterogeneous interface had a minimal RL (RLmin) of
-55.03 dB and a maximum EAB (EABmax) of 4.88 GHz. An EAB of 5.16 GHz (12.84-18 GHz) and an RL of
-40.47 dB were achieved at 1.88 mm . A PANI@FeSiAl composite was fabricated as an EMW absorber by
[75]
in situ oxidative polymerization. The heterogeneous interface between FeSiAl and PANI provided
conductive and polarization loss by charge orientation, interfacial polarization, and defects in the PANI
layer [Figure 3B]. The composite at 1 mm had an RLmin of -37.87 dB . A core-shell hydroxylated boron
[78]
nitride (BN-OH)@Fe O @PANI nanocomposite was fabricated as an EMW absorber by in-situ growth. The
4
3
Fe O and conductive PANI resulted in magnetic and electrical loss, and the EMW had multi-reflection in
3
4
the composite [Figure 3C]. The RLmin reached -49.85 dB at 11.36 GHz, and the EAB reached 8 GHz (8.5-
16.5 GHz) at 3 mm. The TC of the composite with dopamine and hydroxyl as interfacial modifiers was
0.98 W·m ·K -1[35] . PANI/La-doped BaFe O (PANI/La-BaM) composite was developed. With 10% of La
-1
19
12
concentration, the RL and EAB of the composite reached -47.83 dB and 3.98 GHz. This was attributed to
conductivity loss and dipole polarization from PANI, eddy current from La-BaM, multi-reflection and
scattering, and interfacial polarization . A MoS /Fe O /PANI nanocomposite was fabricated. The
[80]
4
3
2
composite had optimized impedance matching and multi-interfacial polarization; the RLmin reached
50.3 dB at 2.6 mm and the EAB reached 5.1 GHz. The EMW absorption was realized in the whole X and
Ku-band .
[76]
A PANI/sludge fly ash material was fabricated via interfacial polymerization. The composite at 2.82 mm had
an RL of -54.11 dB at 10.00 GHz with an EAB of 4.08 GHz. It was ascribed to the combined effect of
magnetic and dielectric loss . Acrylonitrile-methylmethacrylate copolymer C microsphere was modified
[79]
with capsaicin-like 3,5-dimethylphenol derivative (DMPD) to fabricate a dielectric EM absorption material.
Functional groups of C-O, -C-N, -NO and dipole polarization were introduced by DMPD. The
heterointerfaces increased the interface polarization. The RLmin of -63.10 and EABmax of 6.81 GHz (8.95-
[81]
15.76 GHz) were achieved at 2.5 mm . PANI/biomass-derived porous C (BPC) composites were prepared.
The PANI prompts heterogeneous interface and interfacial polarization loss. It also acted as a bridge on
BPC to form conductive networks, which improved multi-reflections and scattering, and conduction loss.