Sustainable Competitive Hydrogen Bonding Paradigms: Unlocking Green Superlubricity through Strategic Cluster Manipulation

Liquid additives represent a pivotal strategy for augmenting tribological performance, yet conventional research paradigms predominantly focus on adsorption and film-forming mechanisms while overlooking their influence on base lubricant properties. Herein, we demonstrate a sustainable liquid superlubricity system based on competitive hydrogen bonding, wherein poly(phosphoric acid) (PPA) serves as a ligand-competitive manipulator for choline chloride-based ionic liquid analogues (ILAs). Choline-based ILAs are inherently sustainable base lubricants because they are biodegradable, nontoxic, and derived from renewable sources. The intricate hydrogen bonding interactions and cluster evolution within PPA/ILAs systems were comprehensively elucidated through Raman spectra, 1H NMR, FTIR, and laser particle size analysis. Remarkably, PPA orchestrates dramatic enhancement in cluster particle size and distribution within the ILA matrix, amplifying asymmetric contact configurations while diminishing shear resistance during tribological processes. This synergistic effect enables spontaneous establishment of robust macroscopic superlubricity, manifesting an exceptionally low coefficient of friction (COF < 0.0032) that significantly reduces energy consumption and carbon emissions in mechanical systems. Furthermore, load-carrying capacity exhibits remarkable enhancement from 294 to 541 MPa, representing an 84% increase while extending equipment lifespan. This investigation unveils a transformative perspective on sustainable lubrication through green ILA systems and cluster particle size distribution dynamics, establishing innovative design paradigms for environmentally friendly next-generation liquid lubricant additives that promote sustainable industrial development.