Vertically anchored nano-fold hybrid on h-BN surfaces achieves effective smoke suppression, antibacterial, and thermal conductivity in epoxy resin composites

Abstract

Considering the requirement of environmental and bio-friendliness of flame retardants, there is an urgent need to develop efficient flame retardants based on low-toxicity raw materials. Herein, a nano-fold structure DBN@CoMo-LDH was successfully synthesized by combining layered double hydroxides (LDHs) with hexagonal boron nitride (h-BN), through a sacrificial template approach involving ion-exchange interaction at atmospheric pressure. Thanks to the better compatibility and strong interfacial interactions of hybrids in matrix, epoxy resin (EP) composites can exhibit superior flame retardancy and smoke suppression without loss of mechanical properties. The enhancement and mechanism of fire safety of EP composites were investigated through cone calorimetric test, condensed-phase residue analysis, and gas-phase product analysis. Compared to EP, the peak heat release rate (pHRR), peak smoke production rate (pSPR), total smoke production (TSP), carbon monoxide production rate (COP) and carbon dioxide production rate (CO₂P) of EP/4DBN@CoMo-LDH were reduced by 37.77 %, 62.96 %, 50.45 %, 45.71 % and 40.98 %, respectively. DBN@CoMo-LDH not only promoted the rapid generation of a dense carbon layer, but also effectively suppressed the release of gas phase products. Furthermore, it demonstrates excellent antimicrobial properties against both Staphylococcus aureus and Escherichia coli. Moreover, the unique nano-fold structure can provide a good thermal conduction path in the matrix, improving the thermal conductivity of EP. This study offers a feasible approach for designing high-performance flame retardants, and suggests their potential application in multifunctional EP composites.