Design, Synthesis and Multifunctional Additive Performance of Novel Hindered Phenolic Amide–Esters

Harsh modern industrial working conditions require high-performance lubricants, but traditional additives are limited by single functionality and poor compatibility, driving the development of multifunctional alternatives. Two novel hindered phenolic amide–esters (MADE, DAME) were synthesized and characterized. Their thermal/storage stability, antioxidant and tribological properties in synthetic oil were evaluated, with commercial 1010 and T203 as references. DFT calculations and worn surface analysis were also employed to clarify the lubrication mechanism. The results indicate that MADE exhibits better thermal/storage stability, comprehensive antioxidation and lubricating performance than DAME, with residual mass of 85.3% and 73.2% at 300 °C, respectively. A total of 1 wt.% MADE shortens the running-in period to 200 s (vs. 300 s for base oil), reduces the average. WSD by 12.1% and wear volume by 60.2%. Mechanistically, MADE adsorbs strongly on metal surfaces and forms a protective tribofilm via tribochemical reaction, exhibiting synergistic antioxidant and anti-wear effects. This work establishes a novel and sustainable paradigm for developing next-generation, multifunctional lubricant additives with high performance.