Low friction epoxy coating based on MoS₂ nanosheets-decorated short carbon fibers with multilevel interfaces under dry-conditions

Enhancing the interfacial bonding between short carbon fibers (SCF) and functional fillers is crucial for developing high-performance self-lubricating polymer composites. In this study, a mussel-inspired strategy was employed to construct multilevel interfaces by depositing polydopamine (PDA) layers onto SCF surfaces, enabling the uniform and dense growth of MoS₂ nanosheets. The resulting MoS₂@PDA@SCF hybrid fillers were incorporated into epoxy resin (EP) to fabricate MoS₂@PDA@SCF/EP composites. The PDA interlayer provided abundant active sites that strengthened the interfacial adhesion between MoS₂ and SCF, as well as the compatibility with the EP matrix. Consequently, the optimized composite exhibited a remarkable 113 % increase in tensile strength and a 26.3 % reduction in friction coefficient compared with pure EP, accompanied by improved thermal stability. These enhancements are attributed to the synergistic effects of SCF load transfer, MoS₂ lubrication, and strong interfacial coupling induced by PDA modification. This work offers an effective interfacial engineering strategy for designing high-strength, low-friction polymer coatings adaptable to demanding dry-sliding environments.