Recyclable Surface-Fluffy flocculent MOF coatings for Triple Shields: Fire, heat and noise

Flexible polyurethane foam (FPUF) is characterized by its low density, high elasticity, and superior thermal insulation properties; however, its inherent flammability severely restricts its application in fire-sensitive sectors, such as the construction and electronics industries. In this study, a novel metal–organic framework (MOF) based flame-retardant with a surface-flocculent and porous structure was synthesized and applied onto the surface of FPUF via a facile dip-coating and drying process. This strategy achieved effective flame retardancy and smoke suppression throughout the entire combustion process. Cone calorimetry tests (CCT) showed that for the FPUF-3 sample, the peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) were reduced by 23.6 %, 32.4 %, and 31.2 %. The residual char layer thickened significantly, while the I _D/ I _G ratio decreased from 3.12 to 2.67, indicating a denser and more graphitized char structure. The modified foam not only maintained its original thermal insulation but also exhibited improved sound absorption. Additionally, the flame-retardant coating was easily recovered in ethanol, with a recovery rate of 91 % for the MOF-based filler. In conclusion, this flame-retardant FPUF, with its superior acoustic and thermal insulation properties, shows great potential for applications in modern construction, automotive, and electronic industries.