Title: Molecular dynamics simulation of confined n-alkanes: ordered structure and crystalline bridges

Authors: Xuan Zheng; Hongtao Zhu; Anh Kiet Tieu; Kuiyu Chen

Addresses: School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia ' School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia ' School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia ' School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia

Abstract: A molecular dynamics simulation of confined n-alkanes with different chain length and thickness has been performed. It discusses the film structure and shear stress of thin film at the atomic scale. Specifically, layered structure in thin film is observed due to the strong liquid-solid interaction and small confinement. An explicit two-layer lubricant film that has 'tetratic' order is observed. Without crystalline bridges, the shear stress drops dramatically. For a thin film with up to three layers, the shear stress varies with thickness. This is due to that the number of crystalline bridges varies between ordered layers. When the film thickness increases further, the effect of the interfacial interaction towards the inner film becomes blunt, and the shear stress becomes stable and is dominated by the lubricant chain length.

Keywords: molecular dynamics; simulation; n-alkanes; thin film lubrication; film structure; shear stress; crystalline bridges; interfacial interaction; lubricant chain length.

DOI: 10.1504/IJSURFSE.2014.060491

International Journal of Surface Science and Engineering, 2014 Vol.8 No.2/3, pp.201 - 212

Received: 20 Feb 2013
Accepted: 13 Aug 2013
Published online: 17 May 2014 *

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