Column-to-Beam Architecture Inspires Interface-Engineered MXene Nanosheet/Boron Nitride Nanosheet/Polydopamine Hybrids for Fire Retardants

Thermosetting epoxy resin (EP) has a high fire hazard that generates a lot of heat and toxic fumes, which is considered a prominent drawback that limits the practical application of EP. Therefore, inspired by the column-to-beam architecture, the BN-PDA-MXene nanohybrid was developed via covalent cross-linking and hydrogen bonding. The results showed that the stable column-to-beam architecture not only prevented the stacking of 2D nanosheets but also built a labyrinth-type array in the EP matrix, which was beneficial to enhancing the thermal stability and flame-retardant performance of EP composites. In particular, with the addition of the 2% BN-PDA-MXene nanohybrid, the maximum mass loss rate (MLRmax) of the EP composite was reduced and the char residue increased. Meanwhile, compared with pure EP, there was a marked reduction of 22.2% in the peak heat release rate, demonstrating the suppressed heat release. Furthermore, EP/BN-PDA-MXene had excellent smoke suppression performance, which was mainly reflected by the downward trend of the peak smoke production rate, total smoke production, and peak CO production rate, together with an obvious reduction of 39.9% in smoke factor. By studying the char residue, it was confirmed that the BN-PDA-MXene nanohybrid had a certain inhibitory effect on the fire hazard of EP due to its lamellar barrier effect, as well as the catalytic detoxification and catalytic carbonization of transition elements.