Improved mechanical and tribological properties of bismaleimide composites by surface-functionalized reduced graphene oxide and MoS₂ coated with cyclotriphosphazene polymer

Surface-functionalized reduced graphene oxide and MoS₂ hybrid nanosheets (rGO/MoS₂) were obtained with a poly-(cyclotriphosphazene-co-4,4′-diaminodiphenylmethane) (PZD) polymer coating by a one-pot noncovalent method. The PZD/rGO/MoS₂ hybrid nanoparticles were then chosen as fillers to improve the mechanical and tribological properties of bismaleimide (BMI) resin. The results showed that suitable addition of PZD/rGO/MoS₂ could greatly enhance not only the mechanical and tribological properties but also the thermal stability. A low friction coefficient of 0.06 and volume wear rate of 1.80 × 10^-6 mm³ (N m)^-1 with 0.4 wt% PZD/rGO/MoS₂ were obtained. This is mainly attributed to the unique layered structure of PZD/rGO/MoS₂ hybrid nanoparticles, the enhanced toughness of the composites, good interfacial adhesion and compatibility between PZD/rGO/MoS₂ and the BMI matrix, as well as the synergistic effect between nanosheets of rGO and MoS₂.