Epoxy composites with functionalized molybdenum disulfide nanoplatelet additives

As a typical layered inorganic analogue of graphene, molybdenum disulfide (MoS₂) has gained intensive attention and become a research hotspot due to its unique two dimensional nanostructure and excellent properties. The enhancement in the thermal and mechanical properties of polymer/inorganic nanosheet composites depends strongly on their interfacial interaction. In this study, we exfoliated bulk MoS₂ into nanosheets which were subsequently functionalized using 3-mercaptopropyltriethoxysilane. The functionalized MoS₂ (f-MoS₂) were dispersed in epoxy polymers at loading fractions of up to 1% by weight via ultrasonication and three roll mills. We characterized the tensile, fracture and adhesive properties of the composite and show that f-MoS₂ nanoplatelets are highly effective at enhancing the mechanical properties of the epoxy at very low nanofiller loading fractions (0.1-0.7% by weight). Our results show the potential of functionalized 2D sheets of transition metal dichalcogenides as reinforcing additives in polymeric composites. The results indicate that the glass transition temperature increases significantly for the lower weight fraction composites, from 135 °C for the baseline (unfilled) epoxy to 146 °C at 0.7% f-MoS₂ loading. The apparent shear strength at 120 °C increases significantly for the lower weight fraction composites, from 13.8 MPa for the baseline (unfilled) epoxy to 24.9 MPa at 0.7% f-MoS₂ loading.