Biomimetic galactomannan/bentonite/graphene oxide film with superior mechanical and fire retardant properties by borate cross-linking

With the great demand for high-strength integrated materials in various industries, products from renewable resources were expected to replace petroleum-based materials. Inspired by the hierarchical structure of nacre, in this work, bentonite and graphene oxide (GO) were incorporated into the galactomannan (GM) matrix to prepare a ternary nanocomposite, which was further cross-linked and strengthened with borate. The chemical structure of the composite was analyzed with SEM, FTIR, XPS and XRD, revealing a co-assembly reaction between GO, bentonite and GM, accompanied by the borate crosslinking. This synergistic strengthen effect resulted in a composite possessing a maximum tensile stress and toughness of 231.16 MPa and 4.53 MJ/m(3), respectively, harder than most of the previously reported hemicellulose composites. Moreover, the nanocomposites showed excellent fire retardant property with a limiting oxygen index of 46.8 % due to the introduction of bentonite and GO, which shows potential application in fire-protective insulation, packaging and coating.