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.