Intelligent phase transition of polyimide-based composite foam for dynamic radar/infrared stealth
image: A hierarchical composite foam for intelligent radar/infrared stealth is assembled by combining polyimide foam in its bottom, PI foam/carbon nanotube/anisotropic iron/vanadium dioxide in its middle, and vanadium dioxide coating on its top. The phase transition of VO2 drives the self-regulating minimum reflection loss from -4.17 dB to -61.69 dB under thermal stimulation conditions. Meantime, the design of the bottom-designed PI foam synergizes with the low-emissivity VO2 formed at high temperatures to endow the material with an excellent infrared stealth performance.
Credit: Nano Research, Tsinghua University Press.
Intelligent radar/infrared stealth materials exhibit the capacity to dynamically modulate their radar/infrared stealth performance under different environmental backgrounds, which is of critical importance in military applications. The unique phase transition characteristic of VO₂ effectively promotes significant changes in the conductivity, emissivity, and electromagnetic parameters of the composite foam, thereby motivating the intelligent regulation of radar/infrared stealth performance. However, directly loading VO2 onto the inner surface of the foam makes it difficult to leverage the low emissivity advantage of rutile-phase VO2, thereby reducing its contribution to infrared stealth performance. Simultaneously, the internal conductive network required for radar stealth tends to accelerate heat transfer within the material, leading to increased surface temperatures and consequently enhanced infrared radiation intensity. Therefore, how to design structures that reduce the thermal conductivity of radar-stealth materials while fully utilizing VO2’s low infrared emissivity has become a critical issue for achieving high-performance radar/infrared dual-compatible stealth.
Shuangshuang Li et al. recently outlined “Intelligent phase transition of polyimide-based composite foam for dynamic radar/infrared stealth” to advance research in the field. Lightweight, flexible foam materials are highly suitable for radar/infrared compatible stealth applications. The current research objective is to develop intelligent radar/infrared stealth materials.
The team published their article in Nano Research on February 6, 2026.
“In this article, we present a hierarchical composite foam for intelligent radar/infrared stealth is successfully fabricated by combining polyimide (PI) foam in its bottom, PI foam/carbon nanotube (CNT)/anisotropic iron (Fe)/vanadium dioxide (VO₂) in its middle, and VO₂ coating on its top. As temperature increases above 68 oC, the corresponding VO2 undergoes a phase transition from monoclinic phase to rutile phase, resulting in significant changes in infrared emissivity and electrical conductivity. Benefiting from the low-emissivity of VO₂ coating in R-phase (> 68 oC) and the heat-transfer suppression originated from the thermal insulation of PI foam, the composite can effectively reduce the infrared radiation originated from protected target. Moreover, the change in electrical conductivity of VO2 promotes a significant variation in electromagnetic parameters of the composite foam, resulting in intelligent radar stealth modulation. As a consequence, the corresponding minimum reflection loss value of composite foam can be effectively switched between -4.17 dB and -61.69 dB at the frequency of 9.96 GHz with a sample thickness of 2.36 mm. Therefore, it can be concluded that this study provides a new strategy for the development of intelligent compatible radar/infrared stealth materials to cope with complex battlefield environments,” Shuangshuang Li said.
This work was supported by Henan Provincial Engineering Research Center for Biomedical Materials in Respiratory Diseases Open Research Projects (SWCLGCJS KF02). National Natural Science Foundation of China (52373077) and China Postdoctoral Science Foundation (2024M760348).
DOI Link:
https://doi.org/10.26599/NR.2025.94908303
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.