Supermolecular assembly networks functionalized MXene toward fire-resistant thermoplastic polyurethane nanocomposites

A new N–P–Cu containing supermolecular assembly network (MPCSN) was fabricated with titanium carbide (Ti 3 C 2 T x ) nanosheets through intermolecular forces, and then, the flame-retardant thermoplastic polyurethane (TPU) nanocomposites were synthesized by melt blending. The obtained results of the TPU/Ti 3 C 2 T x -MPCSN system indicated that the temperature corresponding to T 5% of TPU nanocomposites by adding 2% Ti 3 C 2 T x or 2% MPCSN decreased to 269.1 and 311.5 °C, respectively. Simultaneously, a well dispersion of the loading of 1.0 mass% Ti 3 C 2 T x -MPCSN was found in TPU matrix. Accordingly, the thermal stability of TPU can be found to be substantially improved in the thermogravimetric analysis, which was embodied in the mass loss of TPU/Ti 3 C 2 T x -MPCSN-1.0 reached up to 8.47 mass%. Moreover, the cone calorimeter tests revealed that the peak of heat release rate, the total heat release, carbon monoxide production rate and total carbon monoxide yield of the TPU nanocomposite were prominently diminished by 16.1%, 37.5%, 18.8% and 37.6%, respectively. This provides clues to the flame-retardant mechanism of TPU nanocomposites: The modified Ti 3 C 2 T x is combined with MPCSN through a cross-linked network grown on the surface of the carbon layer, which not only prevents the leakage of combustible gas, but also catalyzes the formation of the carbon layer. This work demonstrates a novel design for improved Ti 3 C 2 T x with supramolecularly assembled networks to reduce potential fire risk in practical TPU applications, applying to applications in polymer materials.