Flexible phase change hydrogels for mid-/low-temperature infrared stealth

Infrared stealth technology capable of effectively rendering targets invisible to thermal infrared detectors plays an important role in defense industry and modern military. Therefore, developing novel infrared stealth materials has aroused widespread concern. Phase change materials (PCMs) with thermal storage and management capabilities can modulate temperature to hide infrared radiation, providing a plausible alternative to the rational design of infrared stealth materials. Herein, flexible phase change hydrogels with excellent mechanical and thermophysical properties are fabricated by integrating the hydrogel substrate with phase change microspheres. Owing to the interfacial effect originating from the introduction of the microspheres, the thermal conductivity and the infrared transmittance of the resulting phase change hydrogel are reduced to 0.17 W/(mK) and 0.3%, respectively, enabling the phase change hydrogel to achieve an intriguing infrared stealth function for targets in the mid-/low-temperature range (-20–60 °C). In addition to conforming to arbitrary targets owing to its excellent flexibility and adaptability, the phase change hydrogel can be facilely coated on common fabrics to yield phase change wearable devices, attaining the on-body infrared stealth. This work offers a constructive guidance to prepare high-performance flexible PCMs for emerging infrared stealth applications.