Synthesis and properties of environmentally sound tribological agents based on 1,1-dihydroperfluoropolyoxaalkyl-β-ketosulfonic acids

Abstract

A wide variety of 1,1-dihydroperfluoropolyoxaalkyl-β-ketosulfonic acid salts has been synthesized and characterized for the purpose of investigating the effect of the chemical structure of these additives on the tribological performance of lubricants. The salts are very effective at their ultralow concentrations of 0.004–0.1% in the lubricating medium. The introduction of an additive into the lubricating medium reduces the tribological pair friction coefficient and wear rate by 20–50% relative to the same parameters of unmodified commercial oil samples. The tribological pair friction coefficient and wear rate depend on the physicochemical state of the tribological pair surface, which is determined by the type of cation, additive concentration in the lubricating medium, and load. The preferability orders for the antifriction and antiwear additives examined appear as follows: in terms of tribological pair friction coefficient, f Li < f Al < f Mg < f Zn < f In; in terms of tribological pair wear rate, Li+ < In3+ < Al3+ < In2+ < Zn2+. Tribological tests of the additives and toxicological screening of the additives and their thermal decomposition products, with the availability of raw materials for their preparative synthesis and the simplicity of the synthesis taken into consideration, suggest that the 1,1-dihydroperfluoro-4,7-dioxa-3,6-dimethyldecan-2-onesulfonic acid salts are promising, environmentally friendly additives for lubricants and fuels.