Flexible and transparent polylactic acid/hydrophobically modified nanobagasse cellulose/tannic acid/MXene films with highly efficient ultraviolet shielding

Ultraviolet (UV) radiation is potentially harmful to human health, while traditional petroleum-based conventional UV shielding materials can damage the environment, which necessitates the development of environmentally friendly transparent UV shielding materials. Ti3C2 (MXene) nanosheets were dispersed in a polylactic acid (PLA) matrix via the synergistic effect of hydrophobically modified nanobagasse cellulose (HC-NBC) and tannic acid (TA) to prepare solution-cast transparent UV shielding PLA/HC-NBC/TA/MXene (PLA/NTM) composite films with tunable bandgaps. The bandgap and UV shielding performance of the PLA/NTM composite films were regulated by varying the MXene addition amount. The bandgap of the PLA/NTM composite film with an MXene content of 1 wt% decreased to 2.37 eV, and the UVC, UVB, and UVA shielding ratios were 97.3, 96.9, and 90.8%, respectively. The visible light transmissibility of the PLA/NTM composite film was 41.8%, and its tensile strength increased by 58.4%. Furthermore, molecular dynamics simulations of the PLA/NTM composite system demonstrated that the hydrogen bonds between TA and HC–NBC synergistically promoted MXene dispersion in the PLA matrix, improving the UV shielding and mechanical properties of the PLA/NTM composite films. The findings of this study provide a new technical reference for the preparation of high-performance transparent UV shielding films.