Bioinspired,\nHighly Adhesive, Nanostructured Polymeric\nCoatings for Superhydrophobic Fire-Extinguishing Thermal Insulation\nFoam

Lightweight\npolymeric foam is highly attractive as thermal insulation\nmaterials for energy-saving buildings but is plagued by its inherent\nflammability. Fire-retardant coatings are suggested as an effective\nmeans to solve this problem. However, most of the existing fire-retardant\ncoatings suffer from poor interfacial adhesion to polymeric foam during\nuse. In nature, snails and tree frogs exhibit strong adhesion to a\nvariety of surfaces by interfacial hydrogen-bonding and mechanical\ninterlocking, respectively. Inspired by their adhesion mechanisms,\nwe herein rationally design fire-retardant polymeric coatings with\nphase-separated micro/nanostructures via a facile\nradical copolymerization of hydroxyethyl acrylate (HEA) and sodium\nvinylsulfonate (VS). The resultant waterborne poly­(VS-co-HEA) copolymers exhibit strong interfacial adhesion to rigid polyurethane\n(PU) foam and other substrates, better than most of the current adhesives\nbecause of the combination of interfacial hydrogen-bonding and mechanical\ninterlocking. Besides a superhydrophobic feature, the poly­(VS-co-HEA)-coated PU foam can self-extinguish a flame, exhibiting\na desired V-0 rating during vertical burning and low heat and smoke\nrelease due to its high charring capability, which is superior to\nits previous counterparts. Moreover, the foam thermal insulation is\nwell-preserved and agrees well with theoretical calculations. This\nwork offers a facile biomimetic strategy for creating advanced adhesive\nfire-retardant polymeric coatings for many flammable substrates.