Multi-Scale Bionic Structure Constructs Biomass Flame-Retardant Thermal Insulation Foam Material.

Amid intensifying environmental and energy pressures, sustainable thermal-insulation materials that also provide effective fire protection are increasingly needed for buildings. Cellulose-based foams are promising candidates for building-envelope applications; however, their practical deployment is hindered by limited fire performance, inadequate structural stability, and complex processing. Here, we propose a multiscale biomimetic strategy inspired by mussel adhesion and hierarchical brick-and-mortar architectures. Polydopamine is introduced as an interfacial bridging layer to uniformly immobilize bentonite nanosheets within a cellulose network, enabling the fabrication of high-efficiency flame-retardant cellulose-based biomimetic foam (CBF) through aqueous mechanical foaming and ambient-pressure drying. The resulting CBF exhibits low thermal conductivity alongside improved flame retardancy and environmental compatibility. A cradle-to-grave life-cycle assessment further indicates lower greenhouse-gas emissions and reduced toxicity-related impacts than conventional petroleum-derived foams, while retaining recyclability and biodegradability. Collectively, these results establish a green, scalable route to high-performance, degradable thermal-insulation materials for safer and more energy-efficient buildings.