Green self-assembly of h-BN@PDA@MoS2 nanosheets by polydopamine as fire hazard suppression materials

The design of biobased resources to combine two-dimensional (2D) materials organically to design flame-retardant epoxy resin (EP) meets the requirements of green and sustainable development. The pH-switchable characteristics of the polydopamine (PDA) layer are used in this study as a green bridge to prepare the h-BN/MoS2 assembly via electrostatic force ([email protected]@MoS2). The PDA layer containing amine groups at low pH had a positive charge and excluded cations but passed anions, which provided favorable conditions for self-assembly. The chemical structure and morphology were determined by a series of measurements. [email protected]@MoS2 assembly could enhance thermal stability, flame retardancy, and mechanical strength of EP composites significantly. Compared with pure EP, the addition of 2.0 wt% [email protected]@MoS2 resulted in a 32% and 17.8% decrease in peak heat release rate and total heat release of EP composites. The amount of toxic CO and flammable gas production during combustion was also significantly suppressed. PDA as an adhesive could exert the synergistic flame retardant effort of h-BN and MoS2 nanosheets. Moreover, the [email protected]@MoS2 assembly could form strong interactions with the EP matrix and increase the graphitization degree of char residues. This study provided a novel green route to assemble 2D materials efficiently and promoted its application in the high-performance polymer composites.