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Page 4 of 25 Hao et al. Soft Sci. 2025, 5, 39 https://dx.doi.org/10.20517/ss.2025.48

multi-scattering configurations. Ultimately, we delve into the prospective trajectories of development and
the promising applications of MSMCs, intricately intertwined with the current landscape of research. Our
objective is to furnish theoretical insights and technical references that will serve as a foundation for the
design of high-performance MAMs.

STRUCTURAL DESIGN AND MICROWAVE ABSORPTION MECHANISMS OF MESOSCOPIC
METACOMPOSITES
Structural design of functional units
MSMCs represent an emerging class of materials that synergistically combine materials science with
periodic/aperiodic structural design, whereby dielectric materials are engineered into mesoscopic functional
units and discretely distributed within the transparent matrix to achieve excellent microwave absorption
performance [36,37] . Especially, mesoscale functional units serve as the core absorptive components; the
structure, size, composition, and distribution state within the matrix play a decisive role in the overall
[38]
absorption performance of the material .

In terms of material composition, MSMCs commonly employ materials with high dielectric loss or unique
physical and chemical properties as the substrate for functional units . Carbon-based materials exhibit
[39]
remarkable characteristics including low density, superior dielectric loss properties, outstanding chemical
durability, and excellent mechanical performance [40,41] . Most conductive loss absorbing materials primarily
consist of carbon-based materials, including graphite, graphene, CNTs, and carbon fibers [42,43] . These
materials are further optimized for electromagnetic wave absorption performance through approaches such
as nanosizing, surface modification, and composite assembly. For instance, graphite nanosheets (GNs),
CNTs, and fumed silica particles enabled the formation of multi-layered composite microspheres. The
CNTs bridging adjacent GNs established the fundamental framework, creating a closed conductive
network, which not only enhanced electrical conductivity but also significantly improved electromagnetic
wave dissipation capacity through polarization relaxation at the interface between the two components .
[44]
In addition to the carbon-materials described above, conductive carbon-based materials that excel at
effectively absorbing electromagnetic waves have emerged. These materials exhibit similar physical and
chemical properties to other carbon-based materials, while also possessing multiple electromagnetic wave
loss mechanisms. Graphitic carbon nitride (g-C N ) has demonstrated significant potential as a carbon-
4
3
based electromagnetic wave absorber, owing to its advantageous combination of low density, exceptional
[45]
stability, and tunable electrical conductivity . g-C N has a two-dimensional structure similar to graphene,
3
4
in which sp -carbon nitrogen hybridization produces π-conjugated electronic configurations . The
2
[46]
incorporation of heteroatoms leads to conductivity loss and dipole polarization, thereby contributing to its
high performance as an electromagnetic wave absorber. MXene material is also a new type of two-
[47]
dimensional material similar to graphene . MXene demonstrates exceptional absorbing material properties
due to its ease of preparation, the straightforward modulation of defects and surface functional groups, and
its high conductivity . Furthermore, the expanded interlayer spacing and the incorporation of diverse
[48]
functional groups enhance the coupling between MXene and other types of absorbing materials, thereby
improving the composite performance . The resultant composite absorbent material possesses multiple
[49]
electromagnetic loss mechanisms, which further contribute to its superior absorption capability.
Metal-organic frameworks (MOFs)-derived carbon-based materials have attracted widespread attention due
[50]
to high structural tunability, a large specific surface area, and a uniform pore size distribution . Through
high-temperature carbonization of MOFs, composite materials with tailored pore structures can be
obtained, leading to the formation of numerous defects that further enhance the dissipation of