Lightweight, Thermally Insulating, Fire-Proof Graphite-Cellulose Foam

Foam materials are widely used in packaging and buildings for thermal insulation, sound absorption, shock absorption, and other functions. They are dominated by petroleum-based plastics, most of which, however, are not biodegradable nor fire-proofing, leading to severe plastic pollution and safety concerns. Here, a fire-proofing, thermally insulating, recyclable 3D graphite-cellulose nanofiber (G-CNF) foam fabricated from resource-abundant graphite and cellulose is reported. A freeze-drying-free and scalable ionic crosslinking method is developed to fabricate Cu2+ ionic crosslinked G-CNF (Cu-G-CNF) foam with a low energy consumption and cost. Moreover, the direct foam formation strategy enables local foam manufacturing to fulfil the local demand. The ionic crosslinked G-CNF foam demonstrates excellent water stability (the foam can maintain mechanical robustness even in wet state and recover after being dried in air without deformation), fire resistance (41.7 kW m(-2) vs 214.3 kW m(-2) in the peak value of heat release rate) and a low thermal conductivity (0.05 W/(mK)), without compromising the recyclability, degradability, and mechanical performance of the composite foam. The demonstrated 3D G-CNF foam can potentially replace the commercial plastic-based foam materials, representing a sustainable solution against the "white pollution".