Interface assembly of flower-like Ni-MOF functional MXene towards the fire safety of thermoplastic polyurethanes

In this study, three-dimensional flower-like Ni-MOFs were fabricated and successfully functionalized on multi-terminal lamellar MXene (Ti3C2Tx) by solvothermal method, and their flame retardant application in thermoplastic polyurethanes (TPU) was investigated. As expected, the addition of Ni-MOF@Ti3C2Tx can improve the flame retardancy and smoke suppression properties of TPU. The heat release rate, the smoke release rate, total smoke production, CO and CO2 release of the composite with only 1 wt% MOF@Ti3C2Tx were significantly reduced by 15%, 44%, 26%, 18%, and 8%, respectively. Furthermore, the carbon residues of TPU/Ni-MOF@Ti3C2Tx composites were about 2-5 times that of pure TPU, indicating that the Ni-MOF@Ti3C2Tx can inhibit the thermal degradation of TPU. The mechanism illustrated that the excellent fire safety properties of TPU/Ni-MOF@Ti3C2Tx composites are due to the physical barrier, catalytical carbonization, and gas-phase flame retardant of Ni-MOF@Ti3C2Tx. In this work, the dispersity, thermal stability, and flame retardancy of MXene were improved due to the modification of MXene with Ni-MOF by chemical bonding and physical adsorption, which can broaden the range of applications of MOFs.