Metal-phenolic network green flame retardants

Metal-phenolic networks (MPNs) which integrate the benefits from natural phenolic molecules and metal ions have widely emerged as versatile coating materials in various fields. Although a wide range of MPN utilizations from biomedicine to environment has been well documented, the use of MPNs in the field of flame retardant is still in the infancy. To achieve this goal, tannic acid (TA)-FeIII MPNs as highly efficient and green flame retardant was designed to coating on the surfaces of polyurethane (PU) foams. Due to the excellent carbonization, superior free radical scavenging ability of TA, and condensed-phase action provided by FeIII for catalysing the charring process during combustion, the MPNs coated PU foams could achieve promising flame retardancy performances. Further investigations also indicated that the coated TA-FeIII MPN could successfully inhibit the release rate and total amount of heat and smoke, and the volatilization of harmful gases during the combustion process had also been successfully reduced. This study illustrates a promising and green strategy towards the surface engineering of many substrates by MPNs coating for flame-retardant applications.