Constructing hierarchical structure based on LDH anchored boron-doped g-C3N4 assembled with MnO2 nanosheets towards reducing toxicants generation and fire hazard of epoxy resin

High fire hazard of releasing considerable toxicants and heat is regarded as a notorious issue for hindering the further application of epoxy resin (EP). Hence, a hierarchical structure (MLBCN) based on LDH anchored boron-doped g-C3N4 assembled with MnO2 nanosheets is rationally constructed as flame retardant additive for EP. Concretely, the incorporation of 1.0 wt% MLBCN leads to the decreases of 31.9% and 25.3% in peak heat release rate and total heat release, separately, reflecting the impeded heat release. Meanwhile, the peak smoke production rate and total smoke release are reduced by 37.1% and 33.4%, respectively, corroborating the hindered fire toxicity. The clear evidence for inhibited emissions of toxic CO and NO gases can be acquired from TG-IR spectra. These results collectively confirm the efficacy of MLBCN in reducing the toxicants generation and fire hazard of EP, deriving from its physical barrier, chemical catalyzing and charring promotion actions. Besides, the tensile and flexural strength are improved by 43.9% and 10.6%, by adding 1.0 wt% MLBCN, demonstrating the promoted mechanical performance. Overall, using MLBCN achieves the simultaneous enhancements in fire safety and mechanical capability of polymer. This work may provide valuable inspirations for constructing multicomponent hierarchical structure, optimizing their prospects in polymer-matrix composite and other areas.