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Page 8 of 25 Hao et al. Soft Sci. 2025, 5, 39 https://dx.doi.org/10.20517/ss.2025.48

[76]
attenuation . For instance, in graphene-based MSMCs, the localized conductive networks provided
optimal transport pathways for charge carriers. When electromagnetic waves are incident, a large number of
[78]
charge carriers migrated within the conductive network, resulting in significant conductive loss . As
temperature increases, the discrete distribution of functional units in the matrix restricts charge carriers to
migrating and hopping only within the internal conductive networks, precluding inter-unit transport .
[79]
Therefore, the decoupling of electrical conductivity and impedance matching can be achieved in MSMCs,
ensuring stable electromagnetic wave absorption across a wide temperature range.

ε ’’ represents polarization loss, which is mainly divided into interface polarization and dipole polarization
p
under the microwave frequency band . The interface polarization effect is also known as the Maxwell-
[80]
Wagner-Sillar effect. Heterogeneous interfaces constructed from materials with significant differences in
[81]
Fermi levels can significantly enhance the interfacial polarization ability of composite materials . The
design of porous and hollow structures can also enhance interfacial polarization. Dipole polarization refers
to the motion of dipoles in polarized or non-polar molecules under an alternating electromagnetic field.
The dipole polarization of non-polar molecules in an electromagnetic field is called displacement
polarization, while the dipole polarization of polar molecules in an electromagnetic field is called
orientation polarization. Defect-induced polarization is also an important supplement to polarization
relaxation. Defect sites in absorbers can trap charge carriers and break the balance of charge distribution,
thus leading to the polarization process and corresponding EM energy loss.

The polarization loss holds significant importance in MSMCs. Due to the presence of numerous
heterogeneous interfaces and defect centers within the functional units, bound charges within the dielectric
undergo minute displacements under an electric field, leading to the separation of positive and negative
charge centers and the generation of electric dipoles [82,83] . These dipoles subsequently align and orient
themselves under the influence of the electric field. As the electric field frequency increases, the electric
dipoles exhibit relaxation phenomena, leading to polarization loss caused by the repeated reorientation of
electric dipoles during the relaxation process, which results in the dissipation of electromagnetic wave
energy [84-86] . The phase and interfacial structures are crucial for modulating the electromagnetic parameters
and dictating the electromagnetic wave absorption performance [87,88] . Furthermore, sub-wavelength
functional units can be composed of materials with high Fermi level differences to enhance interface
polarization . In general, the efficiency of polarization loss can be effectively improved by rationally
[89]
designing the structure and optimizing material components.

Multiple reflection and scattering represent a distinctive feature of MSMCs, setting them apart from
traditional wave absorbing materials. Owing to the structural complexity within the material,
electromagnetic waves incident on the surface experience repeated reflection and scattering at the interfaces.
The propagation trajectory of electromagnetic waves is altered by each reflection and scattering, extending
the transmission path length within the material and enhancing energy dissipation through prolonged
wave-matter interactions . Conventional MAMs permit the penetration of electromagnetic waves into the
[90]
composites solely under the condition of satisfied impedance matching, subsequent to which reflection and
scattering phenomena may occur . Nevertheless, when impedance matching deteriorates marginally, most
[91]
of the electromagnetic waves are reflected into free space, resulting in a significant reduction in the
microwave absorption performance of the absorbing material. MSMCs have broken through the strict
impedance matching requirements of traditional MAMs. Owing to the discrete distribution of sub-
wavelength functional units within the matrix, metamaterials demonstrate exceptional anti-reflection
properties. When electromagnetic waves penetrate the interior of metacomposites and interact with the
surfaces of functional units, a portion of the waves propagates into the functional units and undergoes