The Effect of Polythiol‐Functionalized Molybdenum Disulfide Nanosheets on the Bonding Performance of Epoxy Resin Adhesives Under Different Adhesive Layer Thicknesses

ABSTRACT Molybdenum disulfide (MoS 2 ) with a sandwich‐like layered structure is regarded as a highly promising nano‐additive for enhancing the mechanical properties of polymer materials. However, the surface of MoS 2 is inert and lacks any active functional groups, resulting in poor compatibility with the epoxy resin (EP). In this study, MoS 2 was exfoliated by the liquid‐phase exfoliation method, and its surface was functionalized with polythiol. The approach aimed to embed organic molecules into the sulfur vacancy sites on the MoS 2 nanosheet surfaces, thereby modulating the interface between MoS 2 and epoxy resin and enhancing their interfacial interaction. The modified product was characterized in terms of structure, thickness, and morphology. The functionalized MoS 2 (SH‐MoS 2 ) was then incorporated into an epoxy resin to form an adhesive, and the bonding performance of the adhesive was investigated at different adhesive layer thicknesses. Compared with the epoxy adhesive without SH‐MoS 2 , the mechanical and bonding properties of the SH‐MoS 2 /epoxy nanocomposite adhesive were significantly improved. This method yielded an SH‐MoS 2 (0.50 wt.%)/epoxy nanocomposite adhesive that exhibited superior tensile shear performance across 0.1–1 mm bondline thicknesses, with all measured values surpassing 20.7 MPa. The findings offer practical design principles for developing polymer nanocomposite adhesives applicable to wide‐gap structural bonding manufacturing.