In situ growth of polyphosphazene particles on molybdenum disulfide nanosheets for flame retardant and friction application

Herein, polyphosphazene nanoparticle (PPN) functionalized MoS₂ nanosheets have been successfully fabricated through a novel two-step method, involving a simple ball milling of bulk MoS₂ powders to acquire exfoliated MoS₂ nanolayer, followed by high temperature polymerization to achieve MoS₂@PPN nanohybrids. The incorporation of P and N atoms could efficiently reduce the stacking of MoS₂ nanolayers and form large number of active sites. It is noted that introducing well-characterized MoS₂@PPN nanohybrids significantly improve the flame retardancy of epoxy resin (EP), i.e., 30.7% and 23.6% reductions in peak heat release rate and total heat release, respectively. The friction coefficients testing results reveal that the EP/MoS₂@PPN1.0 composite exhibits the lowest friction coefficient value and volume wear rate. The excellent properties of these EP composites result from synergetic coupled effect between PPN and MoS₂ ultrathin nanosheets, as well as improved interface interaction between MoS₂@PPN and EP matrix.