Eco-friendly fractionation of natural straws: sustainable ultralong room-temperature phosphorescence and super anti-ultraviolet materials

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.