Design water-soluble phenolic/zeolitic imidazolate framework-67 flame retardant coating via layer-by-layer assembly technology: Enhanced flame retardancy and smoke suppression of flexible polyurethane foam

This work provides a new strategy to solve the problem that flexible polyurethane foam (FPUF) burns easily and produces a lot of toxic smoke in combustion. In this study, 1 wt% of water-soluble phenolic resin (WSPR) and 0.5 wt% of zeolitic imidazolate framework-67 (ZIF-67) were assembled on the surface of FPUF by electrostatic action. The assembly of the coatings was demonstrated by UV-vis, ATR-FTIR and SEM. Subsequently, the effect of the number of coating layers on the fire safety of FPUF was investigated. The combustion results showed that the introduction of WSPR/ZIF-67 flame retardant coating reduced the PHRR, THR and smoke release of FPUF and inhibited the droplets of the foam during the combustion process. The TG-IR results under nitrogen atmosphere showed that the coating was able to effectively delay the escape time and reduce the content of gaseous toxic products during pyrolysis. This coating is both simple and environmentally friendly in the manufacturing process and can be extended to other polymer matrices to improve fire safety. (C) 2020 Elsevier Ltd. All rights reserved.