Shear-induced boundary film formation from dialkyl sulfides on copper

► Explores the effects of sulfur-carbon stoichiometry and load on the ability of dialkyl sulfides as gas-phase lubricants to reduce friction. ► Friction reduction ability increases with sulfur content, but that friction is preferentially reduced at low normal loads. ► This implies that the rate of shear-induced tribofilm formation is relatively independent of the normal load.