We demonstrate a new green solvent consisting of ionic liquid and polyol to achieve a selective fractionation of lignin from biomass. The lignin from corn straw is rich in syringyl unit and phenolic hydroxyl group, resulting in excellent room-temperature phosphorescence (RTP) performance, antioxidation property and long-term photostability. Flexible film, fiber, aerogel and coatings with an ultralong RTP lifetime of 0.654 s are obtained. The lignin from corn straw completely blocks UV light of 290–100 nm at an extremely low usage due to many p-coumarate units. When the content is as low as 1.54 mg/g, which is two orders of magnitude lower than the previous reports, the corresponding sunscreen cream has a super-high sun protection factor (SPF) of 183.9. More importantly, the lignin self-assembles into nanospheres of 250–350 nm, preventing penetration into the skin. Such easily-available, abundant, low-cost, safe and natural lignin provides an innovative avenue for sustainable optical function materials.

我们展示了一种由离子液体和多元醇组成的新型绿色溶剂，可实现生物质中木质素的选择性分馏。玉米秸秆木质素富含紫丁香基单元和酚羟基，具有优异的室温磷光（RTP）性能、抗氧化性能和长期光稳定性。获得了具有0.654 s超长RTP寿命的柔性薄膜、纤维、气凝胶和涂层。玉米秸秆中的木质素由于含有许多对香豆酸单元，可以以极低的用量完全阻挡 290-100 nm 的紫外线。当含量低至1.54 mg/g，比之前报道低两个数量级时，对应的防晒霜却拥有183.9的超高防晒系数（SPF）。更重要的是，木质素自组装成 250-350 nm 的纳米球，防止渗透到皮肤中。这种易得、丰富、低成本、安全、天然的木质素为可持续光学功能材料提供了一条创新途径。