Thermal Friction Enhancement in Zwitterionic Monolayers
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.
Keywords
Cite
@article{arxiv.2111.09576,
title = {Thermal Friction Enhancement in Zwitterionic Monolayers},
author = {Melisa M. Gianetti and Roberto Guerra and Andrea Vanossi and Michael Urbakh and Nicola Manini},
journal= {arXiv preprint arXiv:2111.09576},
year = {2022}
}