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Page 4 of 34 Yan et al. Soft Sci. 2025, 5, 8 https://dx.doi.org/10.20517/ss.2024.66

T + A + R = 1 (4)

(5)

(6)

According to these formulas, when A > R, the material is an absorption-dominated shielding material, and
vice versa for reflection-dominated shielding materials [61-63] . The loss mechanisms are generally categorized
into dielectric loss, conduction loss, and magnetic loss, all of which influence EMW attenuation to varying
degrees.

Dielectric loss
Dielectricity refers to a material’s ability to dissipate electrostatic energy when exposed to an
electromagnetic field. It is typically expressed through the dielectric constant and dielectric loss. Dielectric
materials display electronic polarization, atomic polarization, and interface polarization in the presence of
electromagnetic fields. When exposed to external electromagnetic fields, the dipoles in dielectric materials
align, causing molecular spin and frictional collisions between adjacent molecules. This process converts
EMW energy into heat, thereby dissipating EMW effectively [64-66] .

Conduction loss
EMI shielding materials are required to have good electrical conductivity which demonstrates high
reflectivity of EMWs. When the EMW enters the material, it undergoes multiple reflections, causing the
energy of the wave to decay. Meanwhile, the material’s internal eddy currents are conducted and
transformed into thermal energy through the material’s resistance, thereby dissipating electromagnetic
energy [67,68] .

Magnetic loss
Magnetic materials exhibit strong magnetization when subjected to an external magnetic field, greatly
[69]
enhancing the strength of the internal magnetic field . In an alternating magnetic field, the change in
magnetic induction lags behind the phase of the magnetic field, a phenomenon known as hysteresis and the
energy dissipated due to hysteresis is termed magnetic loss [70,71] . In the dynamic magnetization process,
energy losses occur not only due to hysteresis but also from eddy currents and natural resonance.

Eddy current loss is defined as the energy dissipation that takes place when a conductive magnetic material
[72]
is exposed to an alternating magnetic field . An induced current is generated during this process,
effectively converting magnetic field energy into electric field energy. The eddy current effect influences the
absorption of EMWs in two ways: first, energy is dissipated during the conversion from magnetic energy to
electrical energy. Second, eddy currents change the dielectric characteristics of the material, leading to a
greater impedance mismatch, causing more EMWs to be reflected at the material surface, effectively
resisting the transmission of EMWs .
[73]

FLEXIBLE EMI PHASE CHANGE COMPOSITES
Flexible EMI composites
Flexible electronic devices offer significant advantages in the information age due to their lightweight
nature. They must demonstrate excellent flexibility, stretchability, and ease of processing . Currently, a
[74]
series of flexible materials have been developed using various components. Among these, polymers with low
density, corrosion resistance, high mechanical properties, adjustable elasticity and other unique advantages