Shan Lu

MXene has emerged as a promising two‐dimensional (2D) lubricant additive due to its layered structure, low interlayer shear strength, and tribochemical activity. However, their structural instability under oxygen‐containing and high‐temperature conditions often leads to oxidation and decomposition, which severely limits their practical use in lubrication systems. In this study, instead of suppressing this transformation, we harness the tribochemically induced in situ evolution of MXene to construct a self‐adaptive lubricating interface for low friction and wear under oil lubrication. Comprehensive interfacial characterizations reveal that tribological loading drives the transformation of MXene into a highly graphitized carbon‐rich tribofilm, while coordination interactions between oleic acid (OA) and MXene facilitate carbon reconstruction at the sliding interface. Reactive molecular dynamics (RMD) simulations further demonstrate that friction‐induced shear promotes Ti–C bond dissociation and carbon graphitization, providing atomistic insights into the dynamic interfacial reconstruction process. The combined effects of tribochemical transformation and molecular coordination promote the formation and progressive reconstruction of a robust graphitized tribofilm, thereby sustaining low friction and enhancing wear resistance. This work provides new insights into the tribological behavior of MXene‐based additives and highlights their potential for high‐performance lubrication in advanced mechanical systems.

Self-healing hydrogels can autonomously repair damage, enhancing their performance stability and broadening their applications as soft devices. Although the incorporation of dynamic interactions enhances self-healing capabilities, it simultaneously weakens the hydrogels’ strength. External stimuli such as heating, while accelerating the healing process, may also lead to dehydration. Developing a stable repair strategy that combines rapid healing and high mechanical strength is challenging. Here, we introduce “salt-welding” for high-strength hydrogels with rapid room temperature self-healing. This is achieved through dynamic borate ester bonds in a salt-responsive poly(methacrylamide) hydrogel. The process involves “salt-fusion” to convert fractures into a viscous liquid for swift healing, followed by “salt-concretion” to toughen the hydrogel. The hydrogels achieve a posthealing strength of 23 megapascals in 95 minutes at room temperature, with near 100% healing efficiency. Leveraging their tunable mechanical strength and rapid healing rate, the hydrogel can be tailored for applications as a reparable wear-resistant material and damping device.

The transverse skin of dolphins exhibits a remarkable drag reduction effect. Although previous studies have identified the drag reduction effect of transverse grooves, no clear guidelines exist regarding the impact of groove parameters on turbulent drag reduction. Hence, this paper suggests a novel numerical study using the Reynolds-averaged Navier–Stokes method to investigate the influence of half-sine wave structure parameters on turbulent drag. The results showed that the aspect ratio of shape parameters significantly affected the drag reduction rate by altering the flow velocity and drag distribution near the wall and increasing the viscous sublayer thickness. Moreover, a novel index friction pressure ratio FPr was introduced to evaluate the drag reduction. It was revealed that the ratio FPr was stable at optimal drag reduction effect regardless of the velocity. By optimizing the FPr, a maximum drag reduction of 29.3% was achieved. These findings provide insight for optimizing transverse groove in drag-reducing surface applications.