Microscopy
Confinement-induced refractive index change
Equipment
Materials
Plain strain moduli for the experimental interfaces
Surface cleaning
Roughness measurement
Friction
Contact area and load-bearing area size and average thickness of liquid layer calculation
Slope, root-mean-square roughness of the surfaces, and pressure
Average thickness measurement during sliding
Connection between theory and experiment
Predicted friction coefficient
Plasticity in glass-on-glass contacts
Calculation of the average contact pressure
Fluorescent liquid adsorption
Change of dry friction coefficient with roughness and waiting time
We plot the viscosity derived from the time-resolved film thickness measurement as a function of the island specific film thickness measured during time-resolved measurements of the friction coefficient (fig. S5A). To estimate whether the viscosity increase is the main reason for the change in friction coefficient, we extrapolated our results for our whole experimental range of ΛI (see fig. S5B).