Boosting flame retardancy of thermoplastic polyurethane: Synergistic effect of nickel phosphide nanoparticles and molybdenum disulfide nanosheets

For the first time, a novel nanohybrid based on nickel phosphide (Ni 2 P) nanoparticles and molybdenum disulfide (MoS 2 ) nanosheets was facilely synthesized for enhancing flame retardancy and smoke suppression of thermoplastic polyurethane (TPU). The synergistic effect on flame retardancy is proposed. TPU composite with 2 wt% Ni 2 P/MoS 2 hybrid exhibits the best overall flame retardancy, while TPU composites with the same amount of individual Ni 2 P nanoparticles and MoS 2 nanosheets are average in performance. Specifically, the 41.2% reduction of peak heat release rate (PHRR) is achieved for TPU/Ni 2 P/MoS 2 composite, which is only 16.8% and 26.4% for TPU/Ni 2 P and TPU/MoS 2 composites, respectively. In addition, a more intact protective char layer of TPU/Ni 2 P/MoS 2 composite can be observed. These results clearly suggest the synergistic effect between Ni 2 P nanoparticles and MoS 2 nanosheets. It is hypothesized that physical barrier effect and chemical catalytic ability of Ni 2 P/MoS 2 hybrid contribute to the dramatic reduction of heat release and smoke production. The strategy proposed here is a simple yet efficient approach to fabricate high-performance MoS 2 -based flame retardants.