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Yan et al. Soft Sci. 2025, 5, 8 https://dx.doi.org/10.20517/ss.2024.66 Page 17 of 34

with specific functions by designing structures. Huang et al., by introducing a boron ester crosslinking
skeleton into PW and ethylene-octene copolymer (EOC), designed a thermal interfacial PCM (TIPCM)
[Figure 6C] to realize a 3D support skeleton with a dynamic crosslinking network thereby maintaining the
[134]
mechanical stability of the TIPCM . The TIPCM exhibits a high energy storage density (178.4 J/g) and an
excellent thermal conductivity (3.23 W·m ·K ). Notably, TIPCM surface is rich in dynamic and non-
-1
-1
conjugated boron ester bonds that can be thermally induced to rearrange networks, reconstruct the
topology of boron ester bonding, and exhibit self-healing properties, meaning that when subjected to
mechanical damage brought about by extreme environments, the unique self-healing ability of TIPCM can
ensure its normal use and prolong its service life, and if it is used in the thermal management of the chip, in
actual tests, TIPCM was found to reduce the operating temperature of a CPU by 67 °C at 5 V,
demonstrating its potential for efficient thermal management, which is an important advantage for the
design of PCMs with excellent thermal storage and special physical properties. In summary, polymer
encapsulation technology combined with various conductive and thermally conductive fillers offers a
promising path for the preparation of highly conductive, thermally conductive, and shape-stable PCCs for
waste heat harvesting and thermal management of electronic products. Summary of properties of different
flexible PCCs is detailed in Table 3.

Flexible EMI PCCs
Researchers have recently investigated polymer-based flexible EMI shielding composites based on fillers
such as MXene, carbon materials, and metal nanoparticles. These composites effectively address the
drawbacks of metal materials in real-world applications, such as their high density, poor weather resistance,
and susceptibility to corrosion . However, a single EMI composite material can no longer satisfy the use
[135]
in many fields, particularly as 5G or even higher communication technology advances; the powerful EMWs
that are converged by electronic micro-devices will cause heat to accumulate. This will not only lower the
equipment’s operational efficiency but also significantly shorten its service life and possibly endanger
people’s health [136-139] . The design of flexible PCCs with both thermal management and electromagnetic
shielding is a matter of urgency.

By incorporating MXene nanomaterials into polymer matrices to form a conductive network, it is possible
to create lightweight, high-performance EMI shielding materials. When PCMs are adsorbed onto this
network, flexible EMI PCCs with excellent thermal management properties are formed, offering significant
potential for various applications. Li et al. obtained a new type of Janus multifunctional film by
encapsulating PCMs in an ultra-flexible EMI film with continuous electrostatic spinning and spraying
technology . The phase change microcapsules are connected with PVA to form a stable “candied fruit
[140]
structure”, and a layer of polylactic acid (PLA) is superimposed on its surface, and finally an ultra-flexible
EMI phase change film is obtained by spraying a conductive layer of MXene on the PLA surface
[Figure 7A]. A large number of spherical PCCs and flexible PVA fibers are integrated to impart excellent
bendability to the film. The strong conductivity of the MXene layer is the main cause of the EMI shielding
effect. When EMW strikes the MXene sheet, a large number of free electrons are attenuated by impedance
matching, which absorbs the energy of the EMW incident on the film surface. This transforms the EMW
energy into thermal energy, which is then released through hysteretic losses. Meanwhile, due to the
foldability of the film, the remaining EMW, after passing through the first MXene layer, encounters a
barrier in the next layer; i.e., the second layer acts as an emissive layer generating multiple internal
reflections leading to a continuous attenuation of the EMW until it is completely absorbed by the structure,
which can be attributed to the reflection coefficient of the folded film being significantly higher than that of
a single film, and thus, through the ingenious origami process, the EMI shielding effect of the composite
film has been improved. Moreover, the incorporation of PCCs with heat storage capacity imparts the film
with excellent phase change temperature regulation and radiation cooling, contributing to effective human