Cellulose-based film material, due to its remarkable physicochemical properties, environmentally friend and low cost, has been widely applied in many high-end areas. However, the lack of functional properties (e.g., flame resistance) except poor mechanical performance severely hinders their further applications. Herein, bamboo-based phosphorylated cellulose nanofibrils (B-PCNFs) were prepared through a simple two-step method composed of phosphorylation and mechanical grinding process. The resultant film prepared via solvent casting process shows an excellent mechanical strength of 115.9 MPa, remarkable elongation at break of 53.1%, high Young's modulus of 2.5 GPa and impressive work of fracture up to 41.8 MJ m⁻³, respectively, which should be contributed to the formation of dense and homogeneous polymer networks reinforced by enhanced multiple interactions. When burned against the flame of alcohol lamp (700–800 °C), B_HL-PCNF film also delivers appealing structural stability even over 25s, demonstrating a prominent flame resistance. Meanwhile, compared to original one, the peak heat release rate (PHRR) and total heat released (THR) of B_HL-PCNF film produce a dramatical reduction, i.e., 87.3% and 86.6% for PHRR and THR, respectively. Based on the evolution of morphological and chemical structure, the highly improved flame resistance is strongly contributed to the synergy of phosphorus containing group and lignin, resulting in a protective layer composed of P_xO_y compound and carbon layer. The proposed mechanism for the enhanced flame retardant property is also declared and clarified. Thereby, this phosphorylated cellulose-based film that integrates outstanding mechanical performance and excellent intrinsically flame resistance holds promising potential candidate in practical applications, such as flame-retardant packaging materials.

纤维素基薄膜材料由于其出色的理化特性，对环境友好和低成本，已被广泛应用于许多高端领域。然而，除了较差的机械性能之外，缺乏功能特性（例如，阻燃性）严重阻碍了它们的进一步应用。在这里，竹基磷酸化纤维素纳米纤维（B-PCNFs）是通过简单的两步法，由磷酸化和机械研磨过程组成的。通过溶剂流延法制备的所得膜显示出115.9 MPa的优异机械强度，53.1％的显着断裂伸长率，2.5 GPa的高杨氏模量以及高达41.8 MJ m ^-3的令人印象深刻的断裂功，这应该有助于形成致密和均质的聚合物网络，并通过增强的多重相互作用来加强。当在酒精灯（700–800°C）的火焰中燃烧时，B _HL -PCNF膜即使在25s内也能提供引人注目的结构稳定性，证明其具有出色的阻燃性。同时，与原始膜相比，B _HL -PCNF膜的峰值放热率（PHRR）和总放热（THR）产生了显着降低，即PHRR和THR分别降低了87.3％和86.6％。根据形态和化学结构的演变，高度改善的阻燃性极大地促进了含磷基团和木质素的协同作用，从而形成了由P _x O组成的保护层_y化合物和碳层。还宣布并阐明了所提出的增强阻燃性能的机理。因此，这种具有优异的机械性能和优异的固有阻燃性的磷酸化纤维素基薄膜在诸如阻燃包装材料的实际应用中具有广阔的前景。