3D-Printed Polylactic Acid/Lignin Films with Great Mechanical Properties and Tunable Functionalities towards Superior UV-Shielding, Haze, and Antioxidant Properties.

Three-dimensional (3D) printing is regarded as a novel technique to realize the customized production of films. However, the relative lack of printable materials with excellent mechanical properties and tailored functionalities seriously restricts its wide application. Herein, a promising multifunctional 3D printing filament was fabricated by incorporating lignin into the polylactic acid (PLA) matrix and firstly applied to film production. The results indicate that lignin was an excellent mechanical reinforcement of the PLA matrix, especially for toughening. Only 0.5% lignin doping improved the toughness by 81.8%. Additionally, 3D-printed films with 0.5-5% lignin exhibited excellent ultraviolet (UV)-blocking capability of 87.4-99.9% for UVB and 65.6-99.8% for UVA, as well as remarkable antioxidant properties, ranging from 24.0% to 79.0%, and high levels of haze, ranging from 63.5% to 92.5%. Moreover, the prepared PLA/lignin (P/L) films based on 3D printing achieved the customization of film production and have potential applications in the fields of packaging, electronic products, medical care, and so forth. Overall, this work not only enriches the 3D printing composites with tailored multifunctionality but also brings the promising potential for the production of customized films.