Green preparation of highly transparent nano-NH₂-UiO(Zr)-66/cellulose composite films with high-strength, superior flame retardant and UV to high-energy blue light shielding performance

From the perspective of sustainable development and practical applications, there is a significant demand for the design of advanced cellulose-based film materials with superior mechanical, optical, and functional properties utilizing environmentally friendly strategies. Herein, biodegradable, mechanically robust and flame-retardant cellulose films with adjustable optical performance were successfully fabricated by in situ synthesis of NH₂-UiO(Zr)-66 via a DMF-free green process at room temperature. The results indicate that the introduction of NH₂-UiO(Zr)-66 enables films to realize a desirable flame retardancy (the limiting oxygen index (LOI) increased significantly from 19.2 % to 32.9 %). The film self-extinguish quickly once removed from the flame, demonstrating a prominent flame resistance. Compared to the original film, the modified films demonstrate a significant reduction in the peak heat release rate and total heat released, decreasing from 186.6 to 26.8 W/g and 19.7 to 1.2 kJ/g, respectively. Encouragingly, the incorporation of nano-NH₂-UiO(Zr)-66 enabled films to achieve excellent UV to high-energy blue light (HEBL) shielding competence (90.8-100 %, 99.6-100 %, and 60.9-89 % for UVB, UVA and HEBL) meanwhile retaining low haze (1.9-2.6 %) and high transmittance (86.2-90.9 %). Furthermore, the incorporation of nano-NH₂-UiO(Zr)-66 was observed to enhance the mechanical strength. Overall, this film presents a promising alternative to conventional plastics used in various applications, including electronic devices and packaging materials.