High-Yield, Cost-Effective Fabrication of High-Aspect-Ratio Polyimide Microstructures for Robust Superhydrophobic Surfaces

Superhydrophobic surfaces (SHS), with their exceptional water-repellent properties, have attracted great interest due to their versatile applications. The robustness of SHS has emerged as an essential issue for practical applications, as SHS are directly exposed to various harsh environments, such as continuous raindrop impact, corrosive media, and extreme temperatures. Polyimide (PI) is an ideal candidate for robust SHS due to its superior mechanical, thermal, and chemical properties. However, the low processability of PI in surface microstructuring has limited its application in SHS. In this study, a high-yield and cost-effective fabrication method for constructing high-aspect-ratio PI microstructures has been developed by controlling the template surface treatment, precursor molecular weight, and vacuum process. This approach achieves an exceptional yield rate of 99.8% and an aspect ratio of 10.7, enabling the construction of various microstructures. The SHS is demonstrated by fabricating microstructures on PI surfaces using the proposed method. The PI SHS exhibits a water contact angle of up to 162° and a roll-off angle of less than 9°. The water repellency withstands 100 tape peeling tests and remains stable after continuous exposure to temperatures up to 250 °C and various chemical reagents for 60 days, which presents excellent robustness against environmental factors.