Thin-film lubrication in the water/octyl v-d-glucopyranoside system: Macroscopic and nanoscopic tribological behavior

The friction properties of the water-based surfactant system C8 (octyl v-d-glucopyranoside) are investigated both at the macro- and nanoscale in ring-on-plate and atomic force microscopy friction experiments, respectively. Surface characterization and measurement of the friction gap during sliding, together with the tribological behavior, show a strong shear rate dependence of the friction behavior. High shear rates of approximately 106 s1 in the macroscopic friction experiments induce a molecular alignment of the surfactants in the friction gap. This generates an anisotropic viscosity which allows a high load to be carried but exhibits low viscosity in the shear direction. When the nanoscale and macroscale friction experiments are normalized to the same shear rate, almost identical frictional behavior is observed in the two regimes.