Renewable nanobrick wall coatings for fire protection of wood

Home-structure fires account for 77% of fire deaths and result in more than US$7·7 billion in property damage every year. Wood is a major component in home construction and decoration due to its mechanical properties, aesthetic appeal and renewability, but its inherent flammability poses an ongoing risk. Layer-by-layer-assembled nanocoatings are effective for improving the fire safety of a variety of substrates, but the heterogeneous nature of wood’s surface complicates this aqueous multilayer process. Two different surface treatments, carboxylation and an alkaline wash, are studied here to increase the surface charge of wood and improve the deposition of nanobrick walls composed of renewable chitosan (CH) and vermiculite (VMT) clay. These treatments improve the penetration and performance of these nanocoatings on wood. Wood pretreated with an alkaline wash and coated with just two CH/VMT bilayers exhibits a time to ignition double that of the uncoated wood. This aqueous surface treatment provides a unique opportunity to improve the safety of wood construction.