Boundary lubrication with a liquid crystal monolayer

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2014
Major/Subject
Mcode
Degree programme
Language
en
Pages
012404/1-9
Series
Physical Review E, Volume 90, Issue 1
Abstract
We study boundary lubrication characteristics of a liquid crystal (LC) monolayer sheared between two crystalline surfaces by nonequilibrium molecular dynamics simulations, using a simplified rigid bead-necklace model of the LC molecules. We consider LC monolayers confined by surfaces with three different atomic structures, subject to different shearing velocities, thus approximating a wide variety of materials and driving conditions. The time dependence of the friction force is studied and correlated with that of the orientational order exhibited by the LC molecules, arising from the competition between the effect of the structure of the confining surfaces and that of the imposed sliding direction. We show that the observed stick-slip events for low shear rates involve order-disorder transitions, and that the LC monolayer no longer has enough time to reorder at high shear rates, resulting in a smooth sliding regime. An irregular stick-slip phase between the regular stick-slip and smooth sliding is observed for intermediate shear rates regardless of the surface structure.
Description
Keywords
friction, lubrication, liquid crystals
Other note
Citation
Chen, W. & Kulju, S. & Foster, Adam S. & Alava, M. J. & Laurson, L. 2014. Boundary lubrication with a liquid crystal monolayer. Physical Review E. Volume 90, Issue 1. 012404/1-9. ISSN 1539-3755 (printed). DOI: 10.1103/physreve.90.012404.