A Mussel‐Inspired Polymer‐Network Tribofilms Deliver Oil‐Based Macroscale Superlubricity on Engineering Steel

ABSTRACT Superlubricity (friction coefficient (COF) ≤ 0.01) offers a promising solution to mitigate the global challenges of friction‐induced energy consumption and material wear. Despite recent advances, developing oil‐based (non‐aqueous) superlubricity systems remain highly challenging, particularly on metallic surfaces. Herein, inspired by mussel adhesive chemistry, we report a novel strategy utilizing the molecular self‐assembly concept to actively construct a tribofilm with ultralow shear resistance, enabling robust oil‐based superlubricity. By incorporating dopamine (DA) as a functional block into an ethylene glycol (EG) lubricant, this system demonstrates an ultralow COF (< 0.01) and an extremely low wear rate (1.9 × 10 ⁻¹⁷ m ³ N ⁻¹ m ⁻¹ ) on the boronized steel throughout a 6‐h (216 000 cycles) durability test. From an atomic perspective, DA molecules play a dual role at the sliding interface: i) undergoing self‐polymerization and capturing EG molecules to form a network‐like carbonaceous tribolayer, and ii) forming strong chemical bonds with the substrate to securely anchor the tribolayer. This tribolayer exhibits low interfacial adhesion, only 20% of that observed with pure EG lubrication, significantly reducing shear strength and energy dissipation, ultimately facilitating superlubricity. This study translates the molecular self‐assembly concept into a broadly applicable tribological solution, opening new avenues for developing next‐generation, high‐performance superlubricity materials.