Page 113 - Read Online

Page 12 of 25 Hao et al. Soft Sci. 2025, 5, 39 https://dx.doi.org/10.20517/ss.2025.48

electromagnetic wave attenuation when micrometer-scale TiN/ZrO films are homogeneously dispersed in a
2
[71]
polydimethylsiloxane (PDMS) matrix . As demonstrated in Figure 3C, the MSMCs exhibited significant
electromagnetic wave dissipation attributed to the synergistic interplay of conductive and polarization losses
within functional units. In stark contrast, TiN/ZrO powders with identical filler loadings displayed
2
negligible microwave absorption, underscoring the pivotal role of mesoscopic architecture in enabling
efficient loss mechanisms. Zhang et al. systematically compared the microwave absorption properties of
bulk graphene aerogels, graphene aerogel microspheres, and graphene powders under the same filler
[96]
content . As shown in Figure 3D, the macroscopic conductive network of graphene aerogel bulk materials
endowed them with strong loss capacity but severely deteriorated the impedance-matching characteristics.
Graphene powders, conversely, exhibit optimal impedance matching but suffer from insufficient loss
capacity, primarily due to agglomeration-induced discontinuous conductive paths. In contrast, MSMCs
constructed from graphene aerogel microspheres strike a balance between impedance matching and loss
capability, enabling the composites to achieve broadband electromagnetic wave dissipation across the entire
X-band.

The interaction among functional units and the substrate plays a pivotal role in determining absorption
performance. Generally, the stable structure of the functional unit ensures that its wave absorption
performance can be fully utilized. For example, functional units with special internal structures, such as
porous structures, could increase the number of reflections and scatterings of electromagnetic waves within
the unit, thereby enhancing energy dissipation. Concurrently, the interface between the functional unit and
the matrix is also a critical region in the absorption process. Charge accumulation and polarization
phenomena at the interface induce additional Maxwell-Wagner relaxation losses, further boosting
absorption efficiency. Studies have demonstrated that the microwave absorption performance of MSMCs
can be substantially enhanced through rational design of functional unit architecture and surface chemistry,
coupled with optimization of matrix-unit interfacial bonding strength. This improvement is often attributed
to synergistic enhancements in impedance matching and dielectric loss mechanisms, underscoring the
critical role of mesoscale structural engineering in advanced microwave absorption materials.

Excellent impedance matching and strong dielectric loss capability
In practical applications, microwave absorbers must maintain stable performance across varying
temperature conditions, making wide-temperature operability a critical requirement. Conventional
macroscale continuous conductive networks experience a significant increase in electron migration rates
and a decrease in electron hopping energy barriers as temperature rises, leading to degraded impedance
matching characteristics and absorption efficiency . To address this issue, traditional strategies focus on
[97]
enhancing high-temperature microwave absorption capability through microscale component and
structural design, specifically by reducing the content of absorbent and enhancing the polarization
ability . However, traditional strategies often achieve impedance matching at elevated temperatures by
[98]
sacrificing loss performance. This trade-off underscores the need for innovative designs that simultaneously
satisfy both impedance matching and strong loss characteristics over a broad temperature range.

The design strategy of MSMCs transforms the macroscopic continuous conductive network into discrete
functional units. Although the increase in temperature enhances the thermal mobility of electrons, charges
can only move within the unit and cannot jump between functional units. The conductivity of
metacomposites does not significantly increase at high temperatures, ensuring satisfactory impedance
matching over a wide temperature range. Furthermore, the abundant conductive network (e.g., CNTs and
graphene) within the sub-wavelength functional units endows it with strong loss capability. Discrete
mesoscopic functional units exhibit temperature-stable microwave absorption characteristics. Upon
electromagnetic wave irradiation, confined electron migration and hopping within the network generate