Construction of multifunctional linear polyphosphazene and molybdenum diselenide hybrids for efficient fire retardant and toughening epoxy resins.

[Display omitted] • The linear polyphosphazene and MoSe 2 hybrid (LPP-MoSe 2) was constructed. • EP/LPP-MoSe 2 exhibits low PHRR, THR, EHC, TSP, CO yield and CO 2 yield. • LPP-MoSe 2 shows synergistic flame retardant effect in gas-phase and condensed-phase. • LPP-MoSe 2 displays significant toughening and strengthening effect on EP. Epoxy resins (EP) are deemed as one kind of most commonly used thermosets, but immanently suffer from inflammability and brittleness. Herein, we report a newly designed hierarchical molybdenum diselenide (MoSe 2) nanotubes assembled from several-layered nanosheets, and then merged with linear polyphosphazene (LPP) for constructing LPP-MoSe 2 hybrids. LPP-MoSe 2 possesses great advantages in improving the properties of EP for their typical nanotube structure and the combination effect of transition metal, phosphorous and nitrogenous compounds. The developed EP/LPP-MoSe 2 composites present obvious reduction in flammability, obtaining a high LOI value of 29% and reaching V-0 rating in UL-94 test. They also exhibit obvious reduction in the heat hazards of EP, such as peak heat release rate (39.0%) and total heat release (24.8%), as well as the toxicity hazards including total smoke production (31.3%) and the yields of CO and CO 2. Gas-phase and condensed-phase mechanism are elucidated to explain the contribution of LPP-MoSe 2 to the fire retardation of EP. Moreover, the addition of LPP-MoSe 2 can also obviously enhance the mechanical properties of EP. The impact strength of EP is only 9 kJ/m2, while EP/LPP-MoSe 2 3.0 can reach up to 14.2 kJ/m2. Based on tensile test, the well-dispersed LPP-MoSe 2 also leads to significant elevation in tensile strength (74.6%) and elongation at break (100%) of EP. Our data demonstrate that LPP-MoSe 2 shows impressive performance in developing high-performance EP composites, thereby broadening the practical application of EP. [ABSTRACT FROM AUTHOR]