Flexible, transparent, and fire-proof cellulose nanofibril films with outstanding flame retardancy
Jierui Ye, Qingtian Xu, Yuebing Gao, Yipeng Liang, Qiang Wu, Guomin Wu, Siqun Wang, Pan Chen, Qian Li
Abstract
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.