Natural lignocellulosic nanofibril film with excellent ultraviolet blocking performance and robust environment resistance.

Due to the current state of ozone layer depletion and potential risk of skin cancer, researches on sustainable cellulose-based films with ultraviolet (UV) blocking capabilities has attracted widespread attention. However, pure cellulose-based film required UV absorbent to be incorporated because of its poor UV blocking ability. In this work, natural lignocellulosic nanofibril (LCNF) film was fabricated by vacuum filtration and pressing process without any complex chemical modification or adding UV absorbers. The residual lignin retained in LCNF was found to act as natural macro-molecular UV absorber. LCNF film with lignin content of 4.89-15.68% exhibited excellent thermal stability, and their UVA and UVB blocking were in the range of 81.4-99.5% and 96.7-100%, respectively. Moreover, LCNF film exhibited stable UV shielding performance under high temperature, UV irradiation, acidic or alkaline conditions, providing LCNF film with a long-term use capacity. Overall, LCNF film is more environmentally friendly and harmless, which shows high potentials in anti-counterfeiting materials, UV protection, and windshields for vehicles.