Physicochemical and Tribological Performance of Bi-Component Supramolecular Gel Lubricants

Here, reported is a new, simple, and nonsynthetic way of in situ preparation of bi-component supramolecular gel lubricants, which are formed by supramolecular self-assembly of bis(2-ethylhexyl) sulfosuccinate (AOT) and aromatic acid derivatives via the noncovalent interaction in the base lubricating oil. The formation mechanism of the gel lubricant was investigated by experimental and theoretical calculations. The results of ¹H nuclear magnetic resonance, ultraviolet, and molecular dynamics simulations show that they formed a network structure through intermolecular hydrogen bonding and π–π stacking, thereby solidifying the base oil to form gel. The rheological and thermal analysis results show that these gels have shear thinning, creep recovery, and excellent thermal stability, and such characteristics make them potential as a lubricant for special mechanical working conditions. Indeed, tribological data also show that compared with commercial mineral oil 500SN, the gel lubricant has excellent lubricity, anti-wear, and load-carrying capacity, which is attributed to the introduction of the anionic surface active agent AOT molecules. Quartz crystal microbalance and X-ray photoelectron spectrometer characterization proves that AOT forms an effective adsorption film and tribochemical reaction film on the contact surface in the process of friction.