Passivation of black phosphorus by triazine-based silica coating: Hierarchical BP@SiO2-N@Co(OH)2 structure for enhanced fire safety and toughness of unsaturated polyester resins

Abstract

The fire and toxic smoke hazards of polymer combustion and the weak oxidation resistance of pure black phosphorus nanosheets (BPNSs) are hot and difficult issues. Here, triazinylsilane and Co(OH)2 nanoflowers are sequentially encapsulated on the surface of BPNSs to generate a novel multifunctional flame retardant (BP@SiO2-N@Co(OH)2), and incorporated into the unsaturated polyester resin (UPR). Specifically, with the addition of 2 wt% BP@SiO2-N@Co(OH)2, the nanocomposite exhibits superior thermal hazard suppression efficiency relative to previous related work. In particular, BP@SiO2-N@Co(OH)2 exhibits a superior ability to suppress toxic smoke than BPNSs, with a 42.3 % reduction in total smoke production (TSP) at 2 wt% flame retardant content. In addition, UPR with 0.5 wt% BP@SiO2@-N@Co(OH)2 achieves 76.5 % increases in impact strength, revealing excellent mechanical properties. Therefore, a novel multifunctional nano flame retardant is successfully synthesized and provided an innovative strategy for the preparation of multifunctional UPR nanocomposites.