Title
Packing of simulated friction modifier additives under confinement
Document Type
Article
Date of Original Version
8-2-2005
Abstract
Molecular dynamics simulations have been conducted to obtain detailed information regarding molecular structure and packing of surfactant-like "friction modifier" (FM) chains adsorbed to two confining surfaces under sliding conditions. The simulations are interpreted via the density profile, position-dependent fluctuations in the density profile, and parallel, interlayer position correlation functions. Heterogeneous FM structures were obtained. The adsorbed FM chains were found to form semi-ordered monolayers perpendicular to the atomically well-defined surface, with distinct segment positions in the density profile. More fluid layers with broader density profiles and larger fluctuations were formed by some unoriented FM chains oriented preferentially parallel to the surface, between the opposing monolayers. Segment position correlations parallel to the surface in the adsorbed layers were found at separations up to 30 Å. These packings persisted for longer than 4 ns under sliding conditions that ranged from 0 to 7.5 m s -1 (0 to 0.075 Å ps -1). Monolayer structures were observed to remain unchanged under a wide range of normal pressures, with the corresponding changes in volume occurring in the gap between monolayers or between a monolayer and trapped fluid. © 2005 American Chemical Society.
Publication Title, e.g., Journal
Langmuir
Volume
21
Issue
16
Citation/Publisher Attribution
Greenfield, Michael L., and Hiroko Ohtani. "Packing of simulated friction modifier additives under confinement." Langmuir 21, 16 (2005): 7568-7578. doi: 10.1021/la046862l.