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Hao et al. Soft Sci. 2025, 5, 39 https://dx.doi.org/10.20517/ss.2025.48 Page 19 of 25

between adjacent microspheres and microscopic pores within individual microspheres improves impedance
matching and facilitates multiple internal reflections and wave scattering. Consequently, the aerogel
microspheres with the smallest size demonstrate the strongest absorption capacity, achieving a maximum
[123]
absorption amplitude of -70 dB, which is attributed to the enhanced reflection and scattering effects .
Larger units, despite higher individual scattering intensity, exhibit reduced overall scattering efficiency due
to their lower packing density. The size of functional units can influence the dielectric properties of
materials. In the case of MXene with varying lateral dimensions (105 and 171 μm), larger microsheets
exhibit wider interlayer spacing, which facilitates electron transfer and interfacial polarization, thereby
enhancing both conduction loss and interfacial polarization loss. Consequently, the dielectric performance
[124]
of larger-sized MXene is significantly improved . Therefore, the multiple reflection scattering
performance can be optimized by precisely controlling the scale of functional units, ultimately achieving
remarkable adsorption performance. Altogether, the electrical conductivity, unit size, and arrangement of
functional units synergistically modulate the multiple reflection and scattering processes via their unique
action mechanisms, which provides a theoretical basis and design direction for the improvement of
microwave absorption performance of MSMCs. In practical applications, these factors need to be
considered comprehensively to optimize the absorption properties of the materials.

Benefiting from the controllable dispersion and distribution of functional units within the matrix, MSMCs
have outstanding practical application prospects. Furthermore, metacomposites have stable electromagnetic
wave dissipation ability over a wide temperature range, which further enhances their practical application
potential. However, there are still some challenges that need to be overcome before the final practical
application of metacomposites. Foremost among these is the cost-effectiveness dilemma; mesoscopic
architecture often relies on intricate fabrication techniques (e.g., high-precision lithography or multi-step
self-assembly) and rare functional fillers (e.g., noble-metal nanoparticles or tailored nanocarbons), whose
expenses escalate exponentially with production volume. Additionally, it is essential to improve the
mechanical properties of metacomposites while ensuring they meet the performance criteria for microwave
absorption.

CONCLUSION AND OUTLOOK
In summary, the construction of mesoscale functional units preserves their inherent structure in composites
and prevents micro-nano scale filler agglomeration. The discrete distribution of these units modifies the
transmission paths of free charges within the macroscopic conductive network, enabling decoupling of
conductivity and impedance matching. Consequently, subwavelength-scale functional units demonstrate
strong electromagnetic wave loss ability across a wide temperature range while maintaining effective
impedance matching. From an electromagnetic-matter interaction perspective, MSMCs create a novel
microwave absorption paradigm by manipulating reflection and scattering behaviors among functional
units to amplify electromagnetic wave dissipation within the composite matrix. Despite significant
advancements in MSMCs, several critical challenges remain to be addressed for breakthroughs in their
overall performance:

(1) The structural design of subwavelength functional units is currently monotonous. Advancements in 3D
printing technology offer new opportunities for the structural engineering of mesoscopic functional units.
Future efforts should focus on creating hierarchically structured units to better understand their roles in
electromagnetic wave reflection and scattering.

(2) While MSMCs have unique advantages for microwave absorption, the connection between microscopic
and mesoscopic designs is insufficient. Emphasizing multi-scale design is crucial for optimizing microwave