Liquid Metal-Based Supramolecular Oleogel Lubricants Constructed by Dynamic Disulfide and Hydrogen Bonds for Antiwear and Friction Reduction

Supramolecular oleogel is a promising lubricant, showing satisfactory lubrication performance and excellent stability. In this work, a series of gallium-based liquid metal (GLM)-based nano-oleogels were prepared by combining alkylthiol self-assembled GLM nanodroplets (C12@GLM) and α-lipoic acid ester-based dynamic covalently linked supramolecular gels. The dynamic disulfide bonds not only facilitate the formation of dense gel networks but also hinder the sedimentation of nanoparticles by forming coordinate bonds with C12@GLM, thereby conferring great dispersion stability (more than 2 months). The superior friction and wear reduction of nano-oleogels GLM@G-0.5 was observed, with the coefficient of friction decreased to 0.108 from 0.216, wear volume loss reduced by 73.04%, and the load carrying capacity increased from 50 to 550 N, compared with base oil. In conjunction with the shear thinning and creep recovery of the rheological properties of the nano-oleogels, the friction mechanism studies revealed that the gel networks of the nano-oleogels are disrupted under shear, releasing the base oil and nanoparticles. The formation of the lubricating film is assisted by the synergistic action of the nanoadditives and the gel lubricants, and the tribochemical reaction film consisting of iron oxides and iron sulfides, along with GLM nanodroplets.