Modulating Interfacial Energy Dissipation via Potential-Controlled Ion Trapping

As a metal (gold) surface at a given, but variable potential slides past a dielectric (mica) surface at a fixed charge, across aqueous salt solutions, two distinct dissipation regimes may be identified. In regime I, when the gold potential is such that counterions are expelled from between the surfaces, which then come to adhesive contact, the frictional dissipation is high, with coefficient of friction mu approximate to 0.8-0.9. In regime II, when hydrated counterions are trapped between the compressed surfaces, hydration lubrication is active and friction is much lower, mu = 0.05 +/- 0.03. Moreover, the dissipation regime as the surfaces contact is largely retained even when the metal potential changes to the other regime, attributed to the slow kinetics of counterion expulsion from or penetration into the subnanometer intersurface gap. Our results indicate how frictional dissipation between such a conducting/nonconducting couple may be modulated by the potential applied to the metal.

Automated summary

Experimental results reveal that frictional dissipation between metal and dielectric surfaces can significantly vary under different conditions, primarily affected by the potential applied to the metal. Under specific conditions, frictional dissipation is high with a high coefficient of friction, while under another condition, frictional dissipation is lower with a smaller coefficient of friction.