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arXiv · 2111.09576

Thermal Friction Enhancement in Zwitterionic Monolayers

Melisa M. Gianetti·Roberto Guerra·Andrea Vanossi·Michael Urbakh·Nicola Manini
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Abstract

We introduce a model for zwitterionic monolayers and investigate its tribological response to changes in applied load, sliding velocity, and temperature by means of molecular-dynamics simulations. The proposed model exhibits different regimes of motion depending on temperature and sliding velocity. We find a remarkable increase of friction with temperature, which we attribute to the formation and rupture of transient bonds between individual molecules of opposite sliding layers, triggered by the out-of-plane thermal fluctuations of the molecules' orientations. To highlight the effect of the molecular charges, we compare these results with analogous simulations for the charge-free system. These findings are expected to be relevant to nanoscale rheology and tribology experiments of locally-charged lubricated systems such as, e.g., experiments performed on zwitterionic monolayers, phospholipid micelles, or confined polymeric brushes in a surface force apparatus.

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Melisa M. Gianetti, Roberto Guerra, Andrea Vanossi, Michael Urbakh, Nicola Manini. 2021-11-18. Thermal Friction Enhancement in Zwitterionic Monolayers. https://doi.org/10.1021/acs.jpcc.1c09542

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