Interface engineering of MXene towards super-tough and strong polymer nanocomposites with high ductility and excellent fire safety

The integration of high strength, high toughness, and excellent flame retardancy in polymer materials is highly desirable for their practical applications in the industry. However, existing material design strategies often fail to realize such a performance portfolio because of mutually exclusive mechanisms between strength and toughness, and low flame retardancy efficiency of nanofillers in polymers. Here, we reported the preparation of a multifunctional nanohybrid, Ti3C2Tx@MCA, by engineering the surface of titanium carbide nanosheets (Ti3C2Tx, MXene) with melamine cyanurate (MCA) via hydrogen bonding interactions, and subsequent thermoplastic polyurethane (TPU)/Ti3C2Tx@MCA nanocomposites. The resultant TPU nanocomposite containing 3.0 wt% of Ti3C2Tx@MCA shows a high tensile strength of 61.5 MPa, a toughness as high as 175.4 +/- 7.9 MJ m(-3) and a high strain at failure of 588%, and 40% reduction in the peak of heat release rate. Such extraordinary mechanical and fire retardant performances are superior to those of its previous counterparts. Interfacial hydrogen bonding in combination with the "labyrinth" effect and catalytic action of 2D Ti3C2Tx nanosheets are responsible for the outstanding mechanical and fire retardancy properties of TPU nanocomposites. This work provides a new paradigm for integral design of high-performance polymeric materials with excellent mechanical and fire-safe performances portfolio.