Electrochemically prepared black phosphorene micro-powder as flame retardant for epoxy resin

In the field of flame retardant polymer, it is an important challenge by the addition of a small amount of flame retardant to obtain the flame retardancy that meet the application requirements. In this work, a novel nanoscale flame retardant, phosphorene micro-flake was prepared by electrochemical exfoliation of black phosphorus and spiral spray drying technology, which was employed to improve the flame retardancy of the epoxy resin. The influence of phosphorene micro-flakes on the fire-retardant action of epoxy resin-based composite were investigated with a UL-94 test supplemented by thermogravimetric analysis. It was found that the flame retardancy of the phosphorene micro-flakes/epoxy nanocomposite increased with the content of phosphorene micro-flakes. In the UL-94 test, when the content of phosphorene micro-flake was 0.94 wt%, the flame retardancy of phosphorene micro-flake/epoxy nanocomposite achieved the UL-94 V-0 rating, with the bending strength and bending modulus of the nanocomposite were enhanced by more than 30% compared with the neat epoxy resin. Similarly, the bending strength and bending modulus of the nanocomposite increases first and then decreases when the content of black phosphorene micro-flakes increased in the range of 0–0.94 wt%, and that of nanocomposite with 0.2 wt% of black phosphorene micro-flake was more than two times that of nanocomposite without phosphorene. Obviously, as a nano flame retardant, black phosphorene can improve simultaneously both mechanical properties and flame retardancy of the polymer, which attribute to the size effect of nanostructure of black phosphorene.