Durable camouflage materials by polyimide nanofilm with thermal management

• Published in: Applied surface science 2023-01, Vol.608, p.155107, Article 155107
• Main Authors: Lee, Namkyu, Lim, Joon-Soo, Nam, Juyeong, Bae, Hyung Mo, Cho, Hyung Hee
• Format: Article
• Language: English
• Subjects: Camouflage materials; Mechanical durability; Micro-nano structure; Polyimide nanofilm; Radiative cooling
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.155107

We demonstrated the durable IR camouflage materials with nanofilm coating. The mechanical durability of micro-nano structures is critical issue to apply these structures on actual applications. Inspiring that the nanofilm can be transparent based on the Beer-Lambert law, we utilized the nanofilm coating on the camouflage materials to protect the micro-nano structures against the mechanical stress. The results show that the mechanical durability can be demonstrated by SEM image after brushing test as well as the IR camouflage performance can be maintained by IR images. [Display omitted] •Suggesting durable camouflage materials to endure mechanical stress in actual field.•Utilizing the Beer-Lambert law to adopt the nanofilm for protecting micro-nano structures.•Proving mechanical durability against brush test and root-cause-analysis.•Demonstrating IR camouflage performance by comparing IR image with ordinary materials. 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.