Preparation and tribological study of novel amide-based organic friction modifiers

Abstract

We have synthesized two novel amide-based organic friction modifiers(OFMs), namely NIPAOA and NDEAOA, through the addition reaction of oleamine with N-isopropylacrylamide and N, N-dimethylacrylamide. The two OFMs exhibit good solubility in PAO6 base oil. Their tribological performance has been investigated using a line contact both individually and when compounded with the anti-wear additive zinc dialkyldithiophosphate (ZDDP) at temperatures ranging from 40 ℃ to 130 ℃. The results show that NIPAOA and NDEAOA form dual-site adsorption on the tribo-pair surface through the N and O atoms in the head group amide, resulting in the tribo-film exhibiting excellent friction-reducing performance in PAO6 across the temperatures. When compounded with ZDDP, they both exhibit effective synergistic friction-reducing effects, attributed to the formation of a unique tribo-chemical reaction film on the worn surface that contains almost no Fe and its compounds. The formation of the unique tribo-film is partly due to the continuous adsorption of free OFMs on the surface of the formed ZDDP tribo-film, providing a milder contact environment for the tribo-pair, allowing for the continuous polymerization of medium and long-chain zinc dialkyldithiophosphate (ZDDP) to ultimately form a uniform and flat tribo-chemical reaction film which interspersed with nitrogen-containing compounds. Even after long-term testing, the film maintains good stability and abrasion resistance, effectively synergizing friction-reducing and anti-wear properties.