Naturally occurring cellulose nanofibril (CNF) is a major component of plant cell walls and possesses numerous advantages, including a high specific surface area, exceptional strength, abundant availability, renewability, and biodegradability. However, the inherent ignitability of CNF hinders its practical application in advanced functional materials. Herein, we report a novel ternary deep eutectic solvent, designed under mild mechanical grinding, capable of converting cheap bamboo cellulose into phosphorylated cellulose nanofibrils (PCNFs) uniform fibril diameters in the range of 3 − 10 nm. The pure PCNF-fabricated film exhibited excellent flame-retardant and self-extinguishing performances (with a high limiting oxygen index of 70.2%) without adding flame-retardants. Compared with unmodified CNF, the peak heat release rate and total heat release of the PCNF films decreased by 96.7% and 96.9%, respectively. Furthermore, defibrillation significantly improved the mechanical and optical properties of the PCNF films, suggesting considerable potential for applying PCNFs in flame-retardant packaging materials.

中文翻译：

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柔性、透明、防火的纤维素纳米原纤薄膜，具有出色的阻燃性

天然存在的纤维素纳米原纤维（CNF）是植物细胞壁的主要成分，具有许多优点，包括高比表面积、卓越的强度、丰富的可用性、可再生性和可生物降解性。然而，CNF固有的可燃性阻碍了其在先进功能材料中的实际应用。在此，我们报告了一种新型三元低共熔溶剂，在温和的机械研磨下设计，能够将廉价的竹纤维素转化为磷酸化纤维素纳米原纤维（PCNF），原纤维直径在3-10 nm范围内。纯PCNF制备的薄膜在不添加阻燃剂的情况下表现出优异的阻燃和自熄性能（极限氧指数高达70.2%）。与未改性的CNF相比，PCNF薄膜的峰值放热量和总放热量分别降低了96.7%和96.9%。此外，除颤显着改善了 PCNF 薄膜的机械和光学性能，表明 PCNF 在阻燃包装材料中的应用具有巨大的潜力。