Mixed solvent synthesis of polydopamine nanospheres for sustainable multilayer flame retardant nanocoating

Polydopamine has been of great interest in recent years due to its utility for various functional coatings. Unfortunately, traditional deposition methods, such as polymerization from tris(hydroxymethyl)aminomethane [THAM] buffer, require lengthy film formation time. In an effort to overcome this challenge, polydopamine nanospheres were synthesized using a mixed solvent approach and alternately deposited with chitosan via layer-by-layer assembly onto flexible polyurethane foam. This environmentally-benign, multilayer nanocoating results in a 22% decrease in peak heat release rate compared to uncoated polyurethane foam (and eliminates melt dripping), while simultaneously reducing the processing time. This unique processing strategy yields a sustainable flame retardant nanocoating and provides a technological advance for polydopamine utilization.