Novel Polymer Gel Lubricant Functionalized with a Phosphate Anion for Friction Reduction and Film Thickness Enhancement in Multiple Lubrication Conditions
Yongqiang Wang, Qiang Chen, Jian Qin, Xiao Liu, Pingxia Guo, Yurong Wang, Meirong Cai, Feng Guo, Feng Zhou
Abstract
In this study, a supramolecular polymer gelator functionalized with a phosphate anion, PMUS-P, has been successfully synthesized through radical polymerization, and its physicochemical, rheological properties and tribological performance were carefully evaluated as a gel lubricant formed through non-covalent self-assembly in 500SN base oil. The results showed that the gel has a dense network structure, providing excellent stability and mechanical strength. Additionally, the PMUS-P gel exhibits good shear-thinning behavior and excellent creep recovery, effectively avoiding the volatility of lubricants. Under a steel-steel contact, the PMUS-P gel showed excellent tribological performance in long-term wear tests and a high-load, high-frequency, or high-temperature condition. For instance, in long wear tests, the 15 wt % PMUS-P gel showed a 44.90% reduction in average coefficient of friction (COF) compared to 500SN base oil, along with an 88.05% decrease in wear. The lubrication mechanism study revealed that the chemical reactive film formed by friction played a key role in reducing friction and wear, preventing the friction pairs from direct contact. In terms of film-forming properties, the PMUS-P gel demonstrates superior lubrication performance in comparison to 500SN base oil, achieving higher film thickness. Given these advantages, the PMUS-P gel has significant potential for prolonging machinery service life and reducing operational energy consumption, promising to become a new high-performance lubricant.