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Most current flame-retardant nanocoatings for flexible polyurethane foam (PUF) consist of passive barriers, such as clay, graphene oxide, or metal hydroxide. In an effort to develop a polymeric and environmentally benign nanocoating for PUF, positively charged chitosan (CH) and anionic sodium hexametaphosphate (PSP) were deposited using layer-by-layer (LbL) assembly. Only six bilayers of CH/PSP film can withstand flame penetration during exposure to a butane torch (∼1400 °C) for 10 s and stop flame spread on the foam. Additionally, cone calorimetry reveals that the fire growth rate, peak heat release rate, and maximum average rate of heat emission are reduced by 55, 43, and 38%, respectively, compared with uncoated foam. This multilayer thin film quickly dehydrates to form an intumescent charred exoskeleton on the surface of the open-celled structure of polyurethane, inhibiting heat transfer and completely eliminating melt dripping. This entirely polymeric nanocoating provides a safe and effective alternative for reducing the fire hazard of polyurethane foam that is widely used for cushioning and insulation.

Home structure fires are responsible for a majority of fire deaths and injuries. Wood is a key component of home construction due to its excellent mechanical properties and renewability, but it is inherently flammable. This study demonstrates the ability of a waterborne polyelectrolyte complex (PEC) to significantly increase wood's time to ignition, while decreasing peak heat release rate and total heat release. The PEC treatment, comprised of polyethylenimine and sodium hexametaphosphate, preserves the visual aesthetic of the wood and adds little additional weight (ca. 6%), while concurrently increasing flexural modulus and flexural strength. Scanning electron microscope images after torch testing provide evidence of a microintumescent flame retardant mechanism. This unique water‐based coating provides an environmentally benign means to render wood construction much safer.

The increased use of high-voltage electronics requires higher performance dielectric materials. These electrically insulating layers need as high of a dielectric breakdown strength as possible. Herein, multiple polyelectrolyte layer-by-layer assemblies were studied as high-voltage insulators. The influences of molecular weight, polymer backbone architecture, and thermal cross-linking were investigated. It was found that increasing the molecular weight of either the polycation or polyanion increases the breakdown strength due to removal of chain ends that can act as breakdown initiating sites. It was also found that a linear polymer backbone architecture leads to higher breakdown strength when compared to branched polymer architectures. Lastly, through thermal cross-linking, the breakdown strength is increased, and the previously mentioned molecular weight and architecture effects are diminished. These 200–400 nm thick polymer multilayer films exhibit breakdown strengths of ∼300–400 kV/mm. Their simple water-based processing makes them an interesting new option for protecting various types of electronics.

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