Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surface

Abstract Over the past twenty years, thin film lubrication (TFL) theory has been used to characterize the molecular behaviors in lubrication films thinner than 100 nm, effectively bridging the gap between elastohydrodynamic lubrication and boundary lubrication. Unfortunately, to date, the TFL molecu...

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Main Authors: Ming Gao, Haoyu Li, Liran Ma, Yuan Gao, Linwei Ma, Jianbin Luo
Format: Article
Language:English
Published: Tsinghua University Press 2019-06-01
Series:Friction
Subjects:
Online Access:http://link.springer.com/article/10.1007/s40544-019-0279-1
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author Ming Gao
Haoyu Li
Liran Ma
Yuan Gao
Linwei Ma
Jianbin Luo
author_facet Ming Gao
Haoyu Li
Liran Ma
Yuan Gao
Linwei Ma
Jianbin Luo
author_sort Ming Gao
collection DOAJ
description Abstract Over the past twenty years, thin film lubrication (TFL) theory has been used to characterize the molecular behaviors in lubrication films thinner than 100 nm, effectively bridging the gap between elastohydrodynamic lubrication and boundary lubrication. Unfortunately, to date, the TFL molecular model proposed in 1996 has not been directly proven by experimental detection. Herein, a method based on surface-enhanced Raman spectroscopy was developed to show both the packing and orienting of liquid molecules in the TFL regime. By trapping liquid crystal molecules between a structured silver surface and a glass surface, molecular ordering states dominated by shear effect and surface effect were successfully distinguished. A nanosandwich structure consisting of an adsorbed layer, an ordered-molecule layer, and a fluid layer was demonstrated. Molecule imaging in TFL was achieved. Our results illustrate the molecular behaviors and lubrication mechanism in nanoconfined films and facilitate the lubrication design of nanoelectromechanical and microelectromechanical systems.
format Article
id doaj-art-948a201ebac34aa995e82c8ddf4d7d0b
institution Kabale University
issn 2223-7690
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language English
publishDate 2019-06-01
publisher Tsinghua University Press
record_format Article
series Friction
spelling doaj-art-948a201ebac34aa995e82c8ddf4d7d0b2025-08-20T03:49:03ZengTsinghua University PressFriction2223-76902223-77042019-06-017547948810.1007/s40544-019-0279-1Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surfaceMing Gao0Haoyu Li1Liran Ma2Yuan Gao3Linwei Ma4Jianbin Luo5State Key Laboratory of Tribology, Tsinghua UniversityState Key Laboratory of Tribology, Tsinghua UniversityState Key Laboratory of Tribology, Tsinghua UniversityState Key Laboratory of Tribology, Tsinghua UniversitySchool of Materials Science and Engineering, Tsinghua UniversityState Key Laboratory of Tribology, Tsinghua UniversityAbstract Over the past twenty years, thin film lubrication (TFL) theory has been used to characterize the molecular behaviors in lubrication films thinner than 100 nm, effectively bridging the gap between elastohydrodynamic lubrication and boundary lubrication. Unfortunately, to date, the TFL molecular model proposed in 1996 has not been directly proven by experimental detection. Herein, a method based on surface-enhanced Raman spectroscopy was developed to show both the packing and orienting of liquid molecules in the TFL regime. By trapping liquid crystal molecules between a structured silver surface and a glass surface, molecular ordering states dominated by shear effect and surface effect were successfully distinguished. A nanosandwich structure consisting of an adsorbed layer, an ordered-molecule layer, and a fluid layer was demonstrated. Molecule imaging in TFL was achieved. Our results illustrate the molecular behaviors and lubrication mechanism in nanoconfined films and facilitate the lubrication design of nanoelectromechanical and microelectromechanical systems.http://link.springer.com/article/10.1007/s40544-019-0279-1thin film lubricationmolecular behaviorsnematic liquid crystalsurface-enhanced Raman spectroscopylubrication theorynanosandwich structure
spellingShingle Ming Gao
Haoyu Li
Liran Ma
Yuan Gao
Linwei Ma
Jianbin Luo
Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surface
Friction
thin film lubrication
molecular behaviors
nematic liquid crystal
surface-enhanced Raman spectroscopy
lubrication theory
nanosandwich structure
title Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surface
title_full Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surface
title_fullStr Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surface
title_full_unstemmed Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surface
title_short Molecular behaviors in thin film lubrication—Part two: Direct observation of the molecular orientation near the solid surface
title_sort molecular behaviors in thin film lubrication part two direct observation of the molecular orientation near the solid surface
topic thin film lubrication
molecular behaviors
nematic liquid crystal
surface-enhanced Raman spectroscopy
lubrication theory
nanosandwich structure
url http://link.springer.com/article/10.1007/s40544-019-0279-1
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