Nanocellulose composites with enhanced mechanical and flame-retardant properties based on grafting of inorganic organic/multilayer core-shell matter - MSNs-TMSB/DA/TOCNF.

Flame retardant materials are essential for safety, yet their development is often hindered by trade-offs between efficiency, aging resistance, and mechanical properties. Traditional organic flame retardants are inefficient and degrade over time, while inorganic alternatives, despite their effectiveness, are difficult to integrate into composites. Here we showed the synthesis of a novel inorganic silica-based flame retardant, PDA@MSNs-TMSB, which chemically modified nanocellulose fibrils, enhancing flame retardancy, aging resistance, and toughness without compromising integrity. The results showed that, compared to pure TOCNF, the modified nanocellulose materials (TOCNF-PDA@MSNs-TMSB) exhibited a higher limiting oxygen index (46.5 %), reaching the UL-94 V-0 level (GB) rating with self-extinguishing behavior and no flame propagation. In contrast, pure TOCNF had a limiting oxygen index of only 22 % and burned rapidly upon ignition which did not achieve the UL-94 V-0 level rating. The toughness of the modified TOCNF-PDA@MSNs-TMSB was superior to that of pure TOCNF, representing a 37.5 % increase. Combining powerful tenacity, high flame retardancy, and better aging resistance, the flame retardant nanocellulose material from renewable resource shows great potential for flame retardant applications and emits no toxic byproducts post-combustion.