In order to achieve wearable infrared camouflage under the condition of dynamic temperature changes, the team of Professor Yang Dongzhi of Beihua designed a patterned polydimethylsiloxane/MXene/nanoporous PTFE composite film, which can be used as a metafabric, with the spectral selection characteristics of low emission in the mid-infrared band and synchronous high reflection in the sunlight band, as well as high emission in the mid-infrared band and synchronous high absorption in the sunlight band, and realizes both low-temperature "shielded infrared stealth" and high-temperature "compensated thermal camouflage" The integration of camouflage in dynamic scenes. At the same time, through the clever design, the material can achieve intelligent thermal management through a simple "reversible two-sided wear", and the wearing comfort can be adjusted in both hot and cold environments.
Material selection and structural design
Through the selection of materials with specific optical properties and the design of the structure, the superfabric achieves compatibility with reverse mode camouflage and thermal regulation. Firstly, by using the effective heat transfer suppression of the patterned CPDMS layer and the efficient infrared shielding of the MXene layer, NPTFE/MXene/CPDMS (NMC) can not only achieve infrared stealth in the room temperature environment, but also limit the photothermal conversion without hindering the low emission characteristics through the high sunlight reflection and high infrared transmission of the outer NPTFE, and realize the thermal regulation at the skin interface. After flipping, through the high sunlight transmission and infrared emission of the CPDMS layer, the CPDMS/MXene/NPTFE(CMN) superfabric effectively transmits sunlight to the photothermal MXene layer, and then radiates the heat generated by the photothermal/electrothermal conversion to the surface with low loss, actively compensates the surface radiant energy, and realizes the instant thermal camouflage switching under the background of high temperature.
Figure 1. Schematic diagram of shielded infrared stealth and inversely compensated thermal camouflage design of metafabrics, preparation process and characterization
Patterned insulation
The patterned design of the tapered array creates a thermal barrier between the film and the heat source and provides a horizontal heat dissipation path to prevent uneven heat build-up. In particular, due to the negligible contact area between the tip of the patterned array and the heat source, and the unique inclined structure of the cone side, the tapered array structure is more conducive to reducing solid heat conduction and enhancing the reflection of thermal radiation, hindering heat transfer to the surface.
Figure 2. Patterned design and thermal insulation performance of PDMS layer
Shielded IR stealth and synchronous thermal regulation
By synergizing MXene's low IR emissivity and patterned PDMS with effective heat transfer suppression, the ultrafabric has low IR emissivity and regulates the skin interface microclimate to a comfortable state, which has adaptive thermal regulation characteristics compared to traditional fabrics.
Figure 3. After the optical properties of NMC superfabrics and their shielded infrared stealth and thermal regulation performance compensated thermal camouflage are simply "double-sided" flipped, the thermal energy provided by the photothermal/electrothermal conversion is compensated to the surface through the high radiation emission of the external PDMS, and the infrared signature of the surface is adaptively matched to its high-temperature background. In addition, through photothermal and Joule heating, the target can be given preset thermal energy, and the virtual target can be intelligently set to transfer tracking and realize the protection function.
Figure 4. The optical properties of the reverse CMN meta-fabric and its compensating thermal camouflage performance are applied in outdoor simulation stealth applications, and the super-fabric shows excellent infrared camouflage effect in woods, sun-exposed sand, parking lots and snow scenes in different time periods.
Figure 5. In addition to intelligent thermal management, the materials designed in this study have the mechanical properties and flexibility, electromagnetic shielding, self-cleaning functions and environmental stability of wearable fatigue resistance, showing the potential application prospects of smart wearable and multi-functional camouflage.
Figure 6. The comprehensive properties of ultrafabrics, such as electromagnetic shielding, flexibility, self-cleaning and oxidation resistance, are summarized by the patterned thermal insulation design and the selection of materials with specific optical properties, which endow the materials with spectral selectivity in the sunlight and infrared bands, so as to realize the integration of "shielded infrared stealth" and interfacial thermal regulation in low temperature environment and "compensated thermal camouflage" in high temperature background. In addition, the ultra-fabric also has comprehensive properties such as electromagnetic shielding, self-cleaning, and anti-oxidation in humid environments. This work provides a new strategy for designing multifunctional as well as intelligent thermal management materials. This work was carried out in the early stage of the research group on aerogel thermal management (https://doi.org/10.1002/adfm.202212032; https://doi.org/10.1016/j.compscitech.2022.109484; https://doi.org/10.1016/j.cej.2024.153536), thermal camouflage (https://doi.org/10.1021/acsnano.3c00573) and thermal management (https://doi.org/10.1039/D3TA03683A) on the basis of work, It further solves the problem of thinning and compatibility with human thermal management of dual-mode stealth materials that can be applied to dynamic environments, and uses the "Spectral-selective and adjustable patterned polydimethylsiloxane/MXene/nanoporous polytetrafluoroethylene metafabric for dynamic". Infrared Camouflage and Thermal Regulation" was published in the journal Advanced Functional Materials. The first author of the paper is Li Baixue, a doctoral student in the School of Materials Science and Engineering, Beijing University of Chemical Technology, and the corresponding authors are Professor Yang Dongzhi and Professor Yu Zhongzhen of Beijing University of Chemical Technology. This work was supported by the National Natural Science Foundation of China and the Basic Research Fund of the Central Universities.
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Original link:
https://doi.org/10.1002/adfm.202407644 Source: Frontiers of Polymer Science