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

Table 1. Properties of different fillers
EMI fillers Properties Disadvantages
MXene High electrical conductivity flexible size adjustment abundant surface functional groups Prone to oxidation
Nanometal particles High electrical Easy to reunite
AgNWs High electrical Low adhesion
High aspect ratio Atmospheric corrosion
Carbon nanomaterials High specific surface area Easy to reunite
High electrical
High thermal conductivity
Increase roughness
Durability

EMI: Electromagnetic interference; AgNWs: silver nanowires.

are considered potential candidates for flexible substrates [75,76] . These polymers are then supplemented with a
range of excellent conductive fillers [such as MXene, carbon materials (graphene, CNTs), metal
nanoparticles] to prepare composite materials with extremely efficient EMI shielding effect (The different
filler properties are detailed in Table 1).

MXene-based flexible EMI materials
MXene is a new family of two-dimensional nanomaterials known for their excellent electrical conductivity,
flexible size adjustability, strong surface plasmon resonance effects, and abundant surface functional groups,
which have unique properties in EMI shielding [77,78] . Additionally, it has been reported that loading MXene
nanomaterials onto polymeric porous materials can effectively form a conductive network, resulting in
high-performance, lightweight EMI shielding materials [79-81] . Zeng et al. prepared a lightweight, flexible, and
robust MXene-coated polyimide (PI) (C-MXene@PI) porous composite by chemical crosslinking
[82]
techniques and dip coating [Figure 1A] . The material is hydrophobic, oxidation-resistant, and high-
temperature stable, and achieves exceptional EMI shielding performance in the X-band thanks to the
combined effects of the micrometer-sized pores, MXene-based conductive network, and interfacial
polarization between MXene and PI, with an impressive SE of up to 62.50 dB. Moreover, the material also
exhibits excellent electro-thermal properties with an outstandingly fast electro-thermal effect and more
uniform thermal distribution at low voltage and can be securely fastened to the skin to evaluate its
electromechanical sensing capabilities, proving the sensitivity and dependability of the wearable sensor in
detecting human movements, the composites are anticipated to play a significant role in smart gadgets and
flexible electronics of the future. Liu et al. prepared flexible and hydrophobic porous MXene foams from
[83]
thin films assembled with lamellar MXene by a hydrazine-induced foaming process [Figure 1B] . The
material not only exhibits excellent water resistance and durability, but also will play a great role in the fields
of defense, aerospace, and smart wearable electronics due to its highly porous structure that exhibits higher
EMI shielding (70.00 dB) compared with unframed. Zhang et al. prepared polyvinyl alcohol (PVA)-based
EMI shielding composite films with electrostatic spinning, lay-up, and hot-pressing techniques
[84]
[Figure 1C] . The top and bottom layers contain electrostatically spun nanofibers of the magnetic
substance Fe O /PVA composite, and the conductive filler MXene/PVA composite electrostatically spun
4
3
nanofibers are in the intermediate layer, which constructs the process of “absorption-reflection-re-
absorption” of EMWs in the sandwich-structured composite film and realizes the unique interface
polarization between the highly conductive layer and the anti-match layer. This interfacial polarization
enhances EMI shielding performance, achieving a SE of 40.00 dB. Meanwhile, the sandwich structure EMI
shielding composite film exhibits excellent thermal conductivity and mechanical properties and can cope
with diverse changing scenarios, so it has broad application potential in the field of EMI shielding and
human body protection of high-power, lightweight, wearable and flexible electronic devices.