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

ABSTRACT 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.