Nontoxic Cross-Linked Graphitic Carbon Nitride-Alginate-Based Biodegradable Transparent Films for UV and High-Energy Blue Light Shielding.

Flexible, transparent, and biodegradable films that can shield dangerous UV and high-energy blue light (HEBL) are high in demand to satisfy the ever-increasing expectations for environmental sustainability. To achieve this goal, biopolymer alginate is an excellent choice that has an outstanding film-forming ability. However, alginate has the limitation of poor UV and HEBL blocking ability. Thus, in this study, UV and HEBL blocker graphitic carbon nitride (g-C 3 N 4 ) was incorporated in alginate films to enhance the compatibility, applicability, and durability. The ATR-FTIR, TGA, DTG, and FE-SEM results indicated that the composite film formation was due to hydrogen bonding, and the composite films revealed synergistic properties of alginate and g-C 3 N 4 . Though the incorporation of g-C 3 N 4 in films enhanced the mechanical and thermal stabilities of the films, the films were still flexible. The UV-visible transmittance characterization confirmed that the prepared films could block both UV and HEBL radiation while maintaining transparency in visible regions. In experiments involving only 2 wt % g-C 3 N 4 , nearly 90% of UV (200-400 nm) and 95% of HEBL (400-450 nm) irradiation were blocked. Additionally, the inclusion of g-C 3 N 4 also facilitated the biodegradation process of composite films. Moreover, after 6 months, the composite films exhibited excellent UV and HEBL shielding with excellent mechanical durability.