An intumescent flame retardant (DOPO-DAM) containing phosphorus and nitrogen was synthesized via a two-step process and then, it was incorporated into waterborne polyurethane to serve as a reactive flame retardant for preparing flame-retarded WPU (FR-WPU). The chemical structures of DOPO-DAM and FR-WPU were confirmed by ¹H NMR, ³¹P NMR, and FTIR studies. The thermal stability, flame retardancy and mechanical properties of FR-WPU were investigated by TGA, TGA-FIR, Py-GC-MS, limiting oxygen index (LOI) test, SEM-EDS analysis, cone calorimeter test and a universal testing machine. The results showed that the conjugation of DOPO-DAM into WPU induced a slight decline in the thermal stability of FR-WPU. However, the incorporation of DOPO-DAM into WPU significantly enhanced the flame retardancy by reducing the heat release rate (HRR), total heat release (THR), smoke production rate (SPR) and total smoke production (TSP). In addition, the morphology, elemental composition and content of the residual char of the flame-retarded WPU indicated the important function of DOPO-DAM in the condensed phase. Thus, DOPO-DAM exhibited gas-phase and condensed-phase flame retardant effects on the WPU films.

In this work, flame-retardant nanoencapsulated phase change materials (NanoPCMs) containing n-octadecane as the core material and poly(methylmethacrylate) (PMMA) as the shell material were successfully fabricated by introducing diethyl bis(2-hydroxyethyl acrylate)amino methylphosphonate (DEAMP) as the crosslinking agent via miniemulsion polymerization. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analyses confirmed that n-octadecane was successfully encapsulated into the PMMA shell and that the NanoPCMs exhibited a regular spherical profile. The phase change properties, thermal reliability, thermal stability, and flame-retardant properties of NanoPCMs were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), cone calorimeter tests, and limiting oxygen index (LOI) measurements. The DSC results showed that the NanoPCMs possessed a relatively high encapsulation efficiency in the range of 86.5–94.0% for n-octadecane. The thermal properties and durability of the NanoPCMs were almost unchanged after the introduction of DEAMP into the NanoPCMs. The combustion test results showed that the introduction of phosphorus-based flame retardant DEAMP into the NanoPCMs significantly suppressed the heat and smoke releases and, increased the residual weight and LOI value of the EP/NanoPCM composites. In addition, a computer-aided thermal measurement system was created to investigate the thermoregulation properties of the NanoPCMs and the results showed that the addition of NanoPCMs into a gypsum board significantly improved the thermoregulation properties. In conclusion, the flame-retardant NanoPCMs showed considerable potential for thermal energy storage applications, especially in thermoregulated textile and construction fields.