Durable camouflage materials by polyimide nanofilm with thermal management

Durable micro-nano structures are a crucial issue to protect their superior performance from external forces. Although several methods have been suggested to enhance the mechanical durability of micro-nano structures, they are not applicable for camouflage materials to obtain the wanted properties because these methods usually induce undesired resonances and severely reduce the radiative performance. The polyimide nanofilm with great mechanical properties can improve camouflage performance in camouflage materials with increasing the energy dissipation. Additionally, the polyimide nanofilm can be used as a transparent layer based on Beer-lambert's law. These characteristics indicate that the polyimide nanofilm can also be used to protect the micro-nano structures in camouflage materials. Herein, we propose durable camouflage materials for infrared waves with radiative cooling by coating the polyimide nanofilm on the structures. We realize the metal-dielectric-metal-nanofilm structures for the infrared camouflage. Spectral emissivity of durable camouflage materials via measurement and simulation satisfies the requirement for IR camouflage materials. The mechanical durability of proposed camouflage materials is verified by brushing and root cause analysis (RCA) test through visible and scanned electron microscope images. We evaluate that durable camouflage materials maintain their IR camouflage performance factor despite mechanical stress compared to the significant decrease in the performance factor of ordinary camouflage materials.