An ultraviolet shielding material based on lignin nanoparticles engineered with deep eutectic solvents for long-term outdoor application

Ultraviolet radiation (UV) has a significant effect on the wood, and the commonly used UV shielding agents are easily degraded. Lignin is a bio-based UV screening agent and tuning of its nanoparticles is meaningful for realizing the UV shielding properties and stability of composites. With the modification of the deep eutectic solvents based on sulfamic acid and urea, lignin nanoparticles with amino functional groups were prepared, and a protective layer with UV shielding properties was constructed on the surface of the poplar veneer. The phenolic hydroxyl groups, carbonyl groups, and conjugated structure of lignin nanoparticles endowed the composites with the properties of UV shielding, photothermal conversion, and photothermal de-icing. The results of this study provide a benchmark for realizing the low-cost and sustainable preparation of wood composites with UV shielding and are conducive to promoting the high-value application of lignin nanoparticles.