Stress-Induced Electronic/Atomic Interfacial Evolution of MXene/MoS2-Ionic Liquid Heterostructures Enables Adaptive Lubrication in Epoxy Coatings.

Abstract

The tribological performance of MXene/MoS2 heterostructure-based polymer coatings is limited by an incomplete understanding of electronic/atomic interfacial evolution, as well as an insufficient adaptive response to dynamic contact stress under friction conditions, which restricts the realization of load-bearing capacity, lubrication efficiency, and long-term durability. Herein, a multiscale hierarchical hybrid filler (MSIC) is rationally designed by integrating a chitosan-encapsulated MXene/MoS2-[APMIM]Br ionic liquid (IL) heterostructure, and then incorporated into epoxy (EP) to fabricate the self-lubricating composite coatings (MSICP). Nanotribological tests demonstrate that the MSIC exhibits lower and more uniform friction than individual MXene and MoS2, while MSICP significantly reduces wear depth, wear volume, and interfacial adhesion. Density functional theory (DFT) calculations and molecular dynamics (MD) simulations reveal that the sequential interfacial interaction evolution drives enhanced tribological performance. Specifically, sliding initiates IL-mediated boundary lubrication, and further transitions to van der Waals-assisted MXene/MoS2 heterostructure shearing, eventually concluding with strong polar adhesion at exposed MXene surfaces. This evolution suppresses direct solid-solid contact and minimizes electron-cloud overlap, thus reducing interfacial shear and adhesion. At the macroscale, the coating containing 2 wt % MSIC achieves a 70.4% reduction in wear rate (3.7 × 10-4 mm3/N m) compared with EP, confirming the effective translation of nanoscale interfacial regulation into bulk mechanical reinforcement. Machine learning (ML) identifies filler content as the dominant friction-governing factor. Notably, increased filler concentration maintains continuous low-shear channels and buffers plastic deformation, which triggers chitosan microcracking to facilitate on-demand IL release. This work provides a guided strategy for designing high-performance MXene/MoS2 heterostructure-based polymer coatings for wear protection of moving parts in precision machinery systems.