A Novel UV-Shielding and Transparent Polymer Film: When Bioinspired Dopamine–Melanin Hollow Nanoparticles Join Polymers

Abstract

Ultraviolet (UV) light is known to be harmful to human health and cause organic materials to undergo photodegradation. In this Research Article, bioinspired dopamine-melanin solid nanoparticles (Dpa-s NPs) and hollow nanoparticles (Dpa-h NPs) as UV-absorbers were introduced to enhance the UV-shielding performance of polymer. First, Dpa-s NPs were synthesized through autoxidation of dopamine in alkaline aqueous solution. Dpa-h NPs were prepared by the spontaneous oxidative polymerization of dopamine solution onto polystyrene (PS) nanospheres template, followed by removal of the template. Poly(vinyl alcohol) (PVA)/Dpa nanocomposite films were subsequently fabricated by a simple casting solvent. UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of Dpa-s versus Dpa-h NPs. In contrast to PVA/Dpa-s films, PVA/Dpa-h films exhibit stronger UV-shielding capabilities and can almost block the complete UV region (200-400 nm). The excellent UV-shielding performance of the PVA/Dpa-h films mainly arises from multiple absorption because of the hollow structure and large specific area of Dpa-h NPs. Moreover, the wall thickness of Dpa-h NPs can be simply controlled from 28 to 8 nm, depending on the ratio between PS and dopamine. The resulting films with Dpa-h NPs (wall thickness = ∼8 nm) maintained relatively high transparency to visible light because of the thinner wall thickness. The results indicate that the prepared Dpa-h NPs can be used as a novel UV absorber for next-generation transparent UV-shielding materials.

Hydrogen‐bonding assembly of heteropolyacid and poly(vinyl alcohol) for strong, flexible, and transparent UV‐protective films

“…UV–vis spectra of the film samples were recorded on a Lamdba 750 UV–vis spectrophotometer from 200 to 800 nm. The UV‐shielding performance of the films was assessed through the photocatalytic degradation of RhB solution (1 × 10 −5 M, 50 mL) with nano‐TiO 2 (100 mg) in a ZF‐7ND UV lamp (Shanghai Jiapeng Technology Co. Ltd.) with an irradiation wavelength of 365 nm, according to a referenced method . Prior to irradiation, the RhB solution was packed into a beaker and covered with a neat PVA film or a PVA/SiMoA composite film.…”

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

“…The UV protection of PVA and PVA–melanin thin films was verified through the photodegradation of Rhodamine B, following the literature . Briefly, a Rhodamine B solution of 10 −5 M was prepared using ultrapure deionized water (18.2 MΩ cm).…”

“…Polymeric matrixes are interesting components for UV‐protective materials because of their compatibility with different substrates, easy deposition, excellent transparency, and low cost. In particular, poly(vinyl alcohol) (PVA) [Figure (a)] has been widely used as a matrix for UV‐protective materials . Currently, esculetin, graphene, and melanin are the most‐used organic UV absorbers in PVA matrixes.…”

“…In particular, poly(vinyl alcohol) (PVA) [Figure (a)] has been widely used as a matrix for UV‐protective materials . Currently, esculetin, graphene, and melanin are the most‐used organic UV absorbers in PVA matrixes. Among them, melanin is considered one of the most promising candidates because of its broad UV absorption and biodegradability .…”

“…The highest photoprotection from UV irradiation (99.4%) was observed for 5 wt % eumelanin in PVA, which resulted in a considerable decrease in transparency in the visible spectrum. Dopamine–melanin solid and hollow nanoparticles in PVA have also been studied as UV‐protective thin films . The results showed excellent UV‐protective properties, especially for hollow nanoparticles.…”