A graphene@MOFs hybrid based on mechanical force and with the help of a phosphate-containing ligand was obtained for the high efficiency flame retardant of EP

The traditional method of preparing graphene flame retardants is expensive, causes serious pollution to the environment, and poses a threat to health. This article adopts a low-cost, environmentally friendly, and sustainable mechanical ball milling method to exfoliate expandable graphite and uses an organic phosphonic acid ligand as a stripping agent aid to obtain a hybrid of multilayer graphene and phosphate-containing organic acid ligand. Using first principles based density functional theory (DFT) to calculate the binding energy between graphene layers, it was confirmed that ligands as stripping agents can significantly improve the stripping efficiency of graphene. A Ni-MOF coated graphene hybrid (G@Ni-MOF) was prepared by hydrothermal method using the phosphate-containing ligands which dispersed on the graphene surface. As expected, G@Ni-MOF has efficient flame retardant and smoke suppression properties. Compared with pure epoxy resin (EP), the peak heat release rate (PHRR) and total heat release (THR) of EP/G@Ni-MOF 5 were reduced by 43% and 23%, respectively. CO production (PCO) decreased by 49%, and CO₂ production (PCO₂) decreased by 47%. This study supplies a simple method for the design of large-scale preparation of graphene nano flame retardants, which is of great significance for the application of EP materials.