Using a Surface-Forces-Apparatus to Measure Force-Distance Profiles Across Confined Ionic Liquids

In this application note, the interfacial forces between two atomically smooth mica surfaces across the ionic liquid 1-ethyl-3 methylimidazolium-bis trifluorosulfonylimide (EMIM BTI) are measured using an SFA2000 from SurForce LLC. For about 40 years now, the Surface-Forces-Apparatus is a well-established technique to measure distances, normal or friction forces between interacting surfaces across fluid media. It was the first method to directly measure and quantify nowadays well-known interfacial phenomena like Van-derWaals forces, hydrophobic forces, hydration repulsion and electric-double-layer interactions.