Phosphorus‑nitrogen synergistic crosslinking in cellulose acetate-based macromolecular networks: A multifunctional...

The development of high-performance, flame-retardant partially bio-based adhesives is critical for advancing sustainable wood-based construction materials. Melamine, phytic acid, and vanillin were chemically crosslinked to prepare partially bio-based flame retardants (MPV). Cellulose acetate (CA) was subsequently employed as the skeleton of the adhesive, and vanillin was used as the crosslinking agent to co-polymerize with MPV, forming a partially bio-based thermosetting adhesive (CAV-MPV). The results indicated that CAV-MPV adhesives have excellent water resistance and bonding strength. The prepared plywood had a wet shear strength of up to 1.76 MPa and 1.47 MPa after soaking in water at 63 °C and boiling water, respectively. The bonded joints maintained stable adhesion after exposure to acidic and alkaline environments, elevated temperature (160 °C), and liquid nitrogen for 30 days. In addition, the incorporation of the MPV network effectively improved the flame retardant performance of CAV-MPV adhesive. The limiting oxygen index (LOI) of the CAV-MPV adhesive was as high as 85.3% and the poplar veneer coated with it met the V-0 standard through UL 94 test. This study provided a viable strategy for designing multifunctional, flame-retardant partially bio-based adhesives suitable for structural wood composites in construction applications.