Bio-inspired engineering of boron nitride with iron-derived nanocatalyst toward enhanced fire retardancy of epoxy resin

Aiming at improving fire retardancy of epoxy resin (EP), the thermal-exfoliated boron nitride nanosheets (BN) underwent the bio-inspired polydopamine (PDA) nano-coating and in-situ interfacial growth of iron-derived nanocatalyst (Fe) to prepare nanohybrid (BN@PDA@Fe). The design complied with principles: 1) PDA promoted the dispersion of BN in EP matrix and offered active sites for functionalization 2) bio-stabilized iron-derived nanoparticles catalyzed the polyaromatic reaction towards higher quality. Resultantly, 6 wt% BN@PDA@Fe increased limiting oxygen index (LOI) of EP by 10.0% and suppressed fire spread in UL-94 test. The peak heat release rate (pHRR) was reduced by 38.9% with notably suppressed CO and smoke production. Ignition time, as a key aspect of fire safety, was effectively delayed due to enhanced thermal conductivity of BN-based EP nanocomposites. The optimization of char structure due to the interfacial charring accounted for the improved fire retardancy. In perspective, the bio-inspired engineering of BN offered a viable approach to improving fire safety of polymers.