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Role of Trapped Molecules at Sliding Contacts in Lattice-Resolved Friction
Miljan Dašić1, Roy Almog2, Liron Agmon2
1Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, Belgrade 11080, Serbia.
ACS Applied Materials & Interfaces
|August 6, 2024
Summary
Water molecules trapped at the contact interface are essential for maintaining atomic friction resolution in liquid environments. These molecules act as a reservoir, enabling stable nanotribological measurements.
Area of Science:
- Nanotribology
- Surface Science
- Materials Science
Background:
- Atomic friction in liquid environments is critical for surface characterization.
- Previous theories suggested dry contact states for lattice resolution in liquid friction force microscopy.
- The role of surrounding liquid molecules in nanotribological contacts remained unclear.
Purpose of the Study:
- To investigate the influence of water molecules on nanotribological contacts.
- To re-evaluate the assertion of dry contact states in liquid friction force microscopy.
- To understand the mechanism behind lattice-scale friction resolution in liquid environments.
Main Methods:
- Friction force microscopy experiments in liquid environments.
- Molecular dynamics simulations of tip-substrate interactions.
- Analysis of stick-slip patterns to study contact dynamics.
Main Results:
- Water molecules are entrapped at the amorphous SiO2 probe and MoS2 substrate interface.
- Entrapped water molecules influence probe dynamics and prevent long slips.
- Surrounding water acts as a reservoir, replenishing the contact interface during sliding.
Conclusions:
- The presence of trapped water molecules is crucial for lattice-scale friction resolution.
- Liquid molecules are integral to nanotribological contacts, not expelled.
- This finding impacts the engineering of friction mechanisms and surface characterization in liquid media.
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