Phosphate ester-based supramolecular gel lubricants: Achieving high load-carrying capacity and enhanced oil film thickness

The growing demand for reliable, long-lasting equipment performance has heightened the requirements for advanced lubrication solutions. Supramolecular gel lubricants not only mitigate lubricant creep but also enhance lubrication performance through precise molecular design. A novel phosphate ester-type gelator was designed through a simple synthesis route with low-cost raw material. The supramolecular gel lubricants exhibited dual responsiveness to temperature. Reversible sol-gel transitions were achieved by controlling the system within its specific transition temperature range. The gel state restricts the mobility of the lubricant, thereby facilitating its retention and practical development. In contrast, the sol state enhances the interface adsorption of the lubricant molecules, which in turn improves their lubrication performance. In addition, the supramolecular gels exhibited favorable viscoelastic properties, along with prominent shear-thinning behavior and efficient creep recovery performance. Importantly, phosphate-based supramolecular gels exhibit exceptional lubricating properties, including excellent anti-wear behavior, low friction coefficients, and high load-bearing capacities. The lubrication mechanism indicates that under boundary lubrication, the gel rapidly adsorbs onto surfaces. Under stress and thermal influence, it reacts with the substrate to continuously form a high-load-bearing reactive film that protects friction surfaces. In mixed lubrication or elastohydrodynamic lubrication, its unique rheological properties enable the formation of a thick fluid film that reduces wear and friction. These superior properties suggest that supramolecular gel lubricants could replace conventional oils and greases under certain working conditions.