Durable graphite oxide nanocoating for high performing flame retarded foams

Recent developments in the design of water-based coatings encompassing platelet-like nanoparticles have clearly demonstrated the flame retardant potential of this approach for open cell flexible foams. However, the relatively high number of deposition steps required and the limited reports on the durability of the deposited coatings to multiple compression cycles currently represent the main constraints to this approach. This paper addresses these limitations by exploiting a few steps deposition procedure to produce coatings with durable flame retardant properties. Graphite oxide, sodium alginate and sodium hexametaphosphate were combined in a continuous protective coating that extends to the complex three-dimensional structure of the foam. The flame retardant properties of the coatings were evaluated before and after 1000 compression cycles. Even after such multiple deformations, the coated foams showed no melt dripping and self-extinguishment during flammability tests, as well as a highly reduced heat release rates (-70%) and total smoke release (-70%) during cone calorimetry tests. Furthermore, the ability to withstand the penetration of an impinging flame focused on one side of the coated foam for more than 5 min was also maintained. These results clearly demonstrate the durability of the coated foams, opening to real life application fields such as transports seats where high levels of flame retardancy must be maintained for long time under frequent mechanical stress.