Biomimetic, highly adhesive, self-repairing and fire-protective polymeric coatings for polyurethane foam

Lightweight polymer foams are highly desirable as thermal insulation materials for energy-efficient buildings, but their intrinsic flammability poses a major challenge. To address this issue, fire-retardant coatings have emerged as an effective solution. However, most conventional fire-retardant coatings suffer from poor interfacial adhesion to polymer foams during practical applications. In contrast, marine algae in nature exhibit exceptional adhesion to diverse surfaces through interfacial hydrogen bonding and mechanical interlocking. Drawing inspiration from this natural mechanism, we synthesized a flame-retardant acrylic monomer, which was then copolymerized with hydroxyethyl acrylate via radical polymerization to create alternating copolymers. This biomimetic design led to the development of an intrinsically flame-retardant polymer coating that incorporates multiple hydrogen bonding interactions. The resulting copolymer demonstrated remarkable interfacial adhesion to rigid polyurethane foam (PUF) and other substrates, surpassing the performance of most existing adhesives due to strong interfacial hydrogen bonding. Thanks to their high char formation capacity, PUFs coated with the polymer exhibited self-extinguishing properties and achieved the desired UL-94 V-0 rating in vertical burning tests. This study provides a simple and effective biomimetic strategy for designing advanced adhesive flame-retardant polymer coatings, offering promising applications for a wide range of flammable substrates.