Green and facile fabrication of highly fire resistant and smoke suppressive nanocoatings via a biobased polyphenols mediated oxidative/Schiff base dual-crosslinking strategy

Polyurethane foam (PUF) finds widespread application in transportation and interior design owing to its lightweight, thermal insulation, and processability. However, its inherent flammability raises substantial fire safety concerns, limiting use in safety-critical applications. Although flame-retardant coatings offer a viable solution, combining collaborative fire prevention with simple and green manufacturing processes through sophisticated structural design remains a major challenge for interface and applied science. Herein, a self-polymerization/Schiff base assembly strategy is proposed for fabricating dual-crosslinked nanocoatings, which is compatible with a facile one-pot in situ impregnation coating process. The developed coating system exhibits outstanding efficacy in suppressing heat/smoke generation and toxic gas emissions while preserving the mechanical integrity of foam substrates. The uniform and compact nanocoating structure, combined with its multifunctional flame-retardant mechanisms, including synergistic radical quenching, inert gas dilution, and graphitized carbon-rich barrier formation endows the foam with rapid self-extinguishing capability without melt dripping. Notably, the treated foam exhibits significantly reduced heat release (−58.4 %), smoke release (−72.9 % reduction), and toxicity emission. This strategy combines processing simplicity with environmental benefits, enabling scalable production. Our work establishes a new paradigm for designing high-performance, eco-friendly bio-based flame-retardant coatings, advancing next-generation fire-safe polymeric foam materials for widespread applications.