Molecular-Reconfiguration-Driven Tribofilm Engineering: Synergistic Lubrication via Zinc Dialkyldithiophosphate and a Triphenolic Antioxidant

Designing high-performance lubricants with reduced ZDDP reliance requires a systematic insight into harmonizing its antiwear function with the antioxidant role of phenolic additives, which remains an unresolved dilemma. Herein, we report a molecular reconfiguration strategy that transforms ZDDP and a novel hindered triphenolic antioxidant (CDDA) into a zinc-phenolic complex, which, in turn, engineers a hierarchical tribofilm with integrated antiwear, friction-reducing, and load-carrying functions. By combining spectroscopic, computational, and tribological analyses, it is demonstrated that zinc ions from ZDDP selectively bind with terminal phenolic -OH groups of CDDA, forming a stable Z-C complex and releasing dialkyldithiophosphoric acid. Although this transformation discounts oxidation stability, it triggers the in situ construction of a robust and hierarchical tribofilm, with a sulfur-rich "foot layer" for adhesion, a porous zinc pyrophosphate "body layer" for load-bearing, and a graphene-like carbon "head layer" for friction reduction. The resulting tribofilm delivers an 83.1% reduction in wear volume and a maximum load-carrying capacity of 900 N, outperforming individual ZDDP or CDDA formulations. This work confirms that molecular reconfiguration not only enables a drastic reduction in ZDDP reliance but also opens a new pathway for programming a tribofilm structure toward high-performance, environmentally adaptive lubrication.