Construction and flame-retardant performance of layer-by-layer assembled hexagonal boron nitride coatings on flexible polyurethane foams

We first prepared a novel hexagonal boron nitride (h-BN) nanosheet filled flame-retardant coating on the surface of flexible polyurethane foams (FPUFs) by a layer-by-layer assembly method to improve the fire safety of the FPUFs. The microstructures and compositions of the coatings could be well tailored by the alteration of the concentrations of the h-BN dispersions; this resulted in obvious improvements in the thermal stability and flame-retardant properties for the FPUFs under optimal conditions. Particularly, cone calorimetry testing confirmed that the FPUFs coated with a proper amount of h-BN nanosheets effectively reduced the peak of the heat-release rate (50.1%) and CO production (53.8%) of the FPUFs, which demonstrated excellent flame-retardant performance. The excellent flame-retardant properties were attributed to the physical barrier and tortuous-path effects and anisotropic thermal conductivity of the h-BN nanosheets; these retarded the transfer and diffusion of heat toward the polymer matrix. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47839.