Intumescing multilayer thin film deposited on clay-based nanobrick wall to produce self-extinguishing flame retardant polyurethane

Significant loss of life and property results each year from fires fueled by polyurethane found in household furnishings. Established layer-by-layer flame retardant systems were combined to produce a stacked nanocoating for flame retarding polyurethane foam. A bilayer system of chitosan (CH) and vermiculite provides a nanobrick wall exoskeleton, protecting the polyurethane long enough for an intumescing system of CH and ammonium polyphosphate to activate and form a bubbled char layer.