Strong and fire-resistant bamboo enabled by densification and boron nitride/graphene oxide nanocoating

Bamboo is an abundant and fast-growing nature material, which has been used in furniture and buildings. Its strength and fire-resistance are two critical issues for its wide applications. Herein, a high-strength and flame-retardant structural bamboo is obtained by constructing a boron nitride (BN)/graphene oxide (GO) composite nanocoating on the surface of delignified and densified bamboo (D-bamboo), abbreviated as BN/GO@D-bamboo. The two-dimensional BN nanosheets can form a layered structure on the surface of bamboo, providing bamboo with thermal dissipation and physical barrier for significantly improving its fire resistance. As a result, compared with natural bamboo and D-bamboo, the ignition time of BN/GO@D-bamboo is prolonged by 67% and 49%, the maximum heat release rate and total heat release are reduced by 59% and 40%, respectively, the smoke generation is also significantly reduced, showing an excellent flame retardancy and smoke suppression. On the other hand, GO in the composite nanocoating can form hydrogen bonding with the cellulose of bamboo, which in turn endows the coating with strong adhesion (5 B grade). Consequently, the axial tensile strength, bending strength and radial compressive strength of the BN/GO@D-bamboo are significantly improved compared with natural bamboo. Given the excellent flame retardancy and mechanical robustness of BN/GO@D-bamboo, it is expected to be a new generation high-performance sustainable structural material.