Superhydrophobic and transparent multifunctional coating based on stearic acid modified silica for paper relics conservation

Paper relics are of great significance to the progress of human civilization. It is crucial to develop multifunctional materials to protect these paper relics. In this work, the superhydrophobic and transparent multifunctional coating based on stearic acid modified silica (SiO₂) was successfully applied for paper relics conservation via a facile spraying approach. The water contact angle (WCA) of paper relics with multifunctional coating can reach 159.7° exhibiting excellent self-cleaning and weather resistance performance. Moreover, after various aging treatments including dry heat aging, damp heat aging, and ultraviolet aging, the modified paper relics still maintained superhydrophobic performance indicating the excellent stability of the multifunctional coating. Critically, the multifunctional coating did not affect the color of paper relics, the color difference is lower than 1.5. Meanwhile, the multifunctional coating can be easily removed by using anhydrous ethanol without affecting the original morphology of the paper relics. This removable characteristic has been successfully validated on Song Dynasty paper relics, demonstrating this coating is in full compliance with the cultural relics fundamental conservation principles of reversibility, minimal intervention, and authenticity. This work provides an innovative conservation strategy for cultural heritage preservation.