Berlin 2024 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster II

CPP 21.18: Poster

Tuesday, March 19, 2024, 18:00–20:00, Poster E

Molecular dynamics study on the impact of water distribution on nanoscopic friction in case of monolayer MoS₂ — •Miljan Dašić^{1, 2} and Igor Stanković² — ¹Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10, Prague, Czech Republic — ²Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia

We have designed and applied a molecular dynamics (MD) simulation setup for the study of nanoscopic frictional phenomena in case of monolayer MoS₂. Our design represents a typical AFM experiment, comprising an amorphous SiO₂ probe in tribo-contact with a monolayer crystalline MoS₂ plate. Based on experimental conditions, we implemented two clearly distinguishable setups, regarding the water distribution: (1) large quantity of water - SiO₂ probe is fully immersed in water and surrounded by water molecules, and (2) ambient water - water coating is attached to the probe, which is surrounded by lateral vacuum gaps. We determined the force-distance characteristics of a fully-immersed probe at several temperatures, revealing that some water molecules get trapped in the probe-plate gap, with their number decreasing as temperature increases. We obtained well-defined stick-slip friction loops via sliding simulations. Considering the slip regime: fully-immersed probe mainly moves in single-slip regime, while ambient water distribution promotes multiple-slips. Amount of water, and especially its distribution, strongly influence the stick-slip frictional behaviour of the studied tribosystem.

Keywords: nanotribology; molecular dynamics; stick-slip friction; monolayer molybdenum disulfide; impact of water