Effect of Sodium Salicylate on Improving the Lubricating Properties of [C18imC9]Br Wormlike Micelles in Glycerol/Propylene Glycol at Low Temperatures

The formation of long cylindrical wormlike micelles at low temperatures (near 0 °C) is relatively rare. In this work, the effect of different salts on the viscoelasticity of the formed wormlike micelles by the ionic liquid surfactant (1-octadecyl-3-nonyl imidazolium bromide, [C18imC9]Br) and glycerol/1,2-propanediol mixture at low temperature was studied. The rheological measurements revealed that only sodium salicylate (NaSal) can increase the viscoelasticity of [C18imC9]Br wormlike micelles by up to 15 times and the existence of temperature range. When the [C18imC9]Br concentration is fixed, the viscoelasticity of the [C18imC9]Br/NaSal wormlike micelles increases and then decreases with the increase of NaSal concentration. Tribological results show that the [C18imC9]Br/NaSal wormlike micelles have excellent friction reduction and antiwear properties for steel/steel contact at 6.00 °C. The friction coefficient and wear volume of [C18imC9]Br/NaSal wormlike micelles first decrease and then increase with the increase of the NaSal concentration. In addition, their tribological properties are significantly better than those of pure [C18imC9]Br wormlike micelles under the same conditions. The lubrication effect of [C18imC9]Br/NaSal wormlike micelles at low temperatures is improved due to the adhesion of [C18imC9]Br/NaSal wormlike micelles and the protective film formed by the tribochemical reaction.