Covalently functionalized hierarchical MnO₂@LDH nanostructure as building blocks for fire-safe and mechanic-robust epoxy composites

The notorious issue of high fire hazard, including the generation of considerable heat and release of plentiful toxic volatiles, is recognized as the bottleneck of extensive use of epoxy resin (EP). Hence, a covalently functionalized hierarchical MnO₂@LDH nanostructure (FA-MnO₂@LDH) is rationally designed to alleviate these problems. With the incorporation of 2.0 wt% FA-MnO₂@LDH, the peak heat release rate and total heat release are reduced by 44.9% and 33.1%, while the total smoke production is decreased by 50.2%, corroborating the greatly impaired heat and smoke emissions. Meanwhile, the reductions on peak CO production rate and total CO production are 46.3% and 41.3%, demonstrating the markedly impeded CO emission. Moreover, the peak CO₂ production rate and total CO₂ production are reduced by 46.7% and 30.0%, signifying the inhibited burning. Thermogravimetric analysis-infrared spectrometry results also confirm the impeded releases of CO and NO gases. The merit of FA-MnO₂@LDH is also confirmed via the flame retardation comparison with other reported fillers. Stemming from the well-generated hierarchical nanostructure-polymer interfaces, the mechanical property is also promoted. Hence, this investigation can provide useful inspirations for fabricating fire-safe and mechanic-robust polymer composites via designing hierarchically tailored nanostructure.