Ultraviolet‐protective thin film based on PVA–melanin/rod‐coated silver nanowires and its application as a transparent capacitor

ABSTRACT Melanin is a biopigment in many organisms with interesting intrinsic properties suitable for emerging and sustainable technologies. In this work, we report the fabrication of transparent ultraviolet (UV)‐protective thin films based on synthetic melanin in poly(vinyl alcohol) (PVA) matrixes. Melanin was synthesized through the auto‐oxidation of l‐3,4‐dihydroxyphenylalanine (l‐DOPA) under oxygen pressure, resulting in excellent solubility in water. A thin film with a composition of 3 wt % melanin (synthesized at 6 atm oxygen pressure) and silver nanowires (AgNWs) deposited on the surface has good transparency in visible light and 100% UV irradiation photoprotection. Encapsulated PVA–melanin/AgNW films dipped in water for 7 days retained 98% of their UV irradiation photoprotection. Moreover, using a transparent conductive oxide substrate, this UV‐protective system can be simultaneously used as a transparent capacitor. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47805.