Molecular dynamics simulations to aid the rational design of organic friction modifiers

Davidson, James; Hinchley, Sarah L.; Harris, Steven G.; Parkin, Andrew; Parsons, Simon; Tasker, Peter A.

doi:10.1016/j.jmgm.2006.03.006

Cited by 33 publications

(23 citation statements)

References 22 publications

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“…Davidson et al [228] performed EMD simulations to help elucidate structure-activity relationships of mono-, di-, and tri-oleyl glyceride OFMs. Mono-glyceride molecules with two hydroxyl groups and one alkenyl chain packed more efficiently than di-glycerides which contain one hydroxyl group and two alkenyl chains.…”

Section: Film Structurementioning

confidence: 99%

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

2018

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Nonequilibrium molecular dynamics (NEMD) simulations have provided unique insights into the nanoscale behaviour of lubricants under shear. This review discusses the early history of NEMD and its progression from a tool to corroborate theories of the liquid state, to an instrument that can directly evaluate important fluid properties, towards a potential design tool in tribology. The key methodological advances which have allowed this evolution are also highlighted. This is followed by a summary of bulk and confined NEMD simulations of liquid lubricants and lubricant additives, as they have progressed from simple atomic fluids to ever more complex, realistic molecules. The future outlook of NEMD in tribology, including the inclusion of chemical reactivity for additives, and coupling to continuum methods for large systems, is also briefly discussed.

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Section: Film Structurementioning

confidence: 99%

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

2018

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“…Equilibrium and non-equilibrium molecular dynamics (MD) simulations have been used extensively to examine the structure, dynamics, and tribological properties of lubricants [5,6]. Examples include pure polymer melts and hydrocarbons [7,8,9,10,11,12,13,14], silanes [15], fatty acids and amines [16,17,18,19,20,21], glycerin [22], glycerides [23], zinc dialkyldithiophosphates [24], MoS 2 [25,26], room-temperature ionic liquids [27,28], and carbon nanoparticles [29]. Fig.…”

Section: Introductionmentioning

confidence: 99%

Molecular adsorption, self-assembly, and friction in lubricants

Apóstolo

Tsagkaropoulou

Camp

2019

Journal of Molecular Liquids

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Lubricants are complex fluids consisting of a base oil and many different additives, and are used to control friction and wear between solid inorganic surfaces in relative motion. A review of recent work on molecular simulations of lubricants is given. It is shown that simulations can be used to uncover a lot of interesting behaviour, including additive adsorption, additive self-assembly, and a competition between the two. The specific examples to be discussed are: the adsorption of stearic acid and oleic acid in squalane on iron-oxide surfaces; the self-assembly of glycerol monooleate in bulk n-heptane; the adsorption and friction of glycerol monooleate in squalane on iron-oxide surfaces; and the conformations of functionalised copolymers in bulk n-heptane. The structures adopted by the additives can be correlated with the observed frictional properties, opening up the possibility of molecular-level design of new lubricants.

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“…[15][16][17] Greenfield and Ohtari studied confined fluids of friction-modifying additives in 1999, 18 and more recently, Davidson et al investigated surface adsorption of organic friction modifiers. 19 MD simulations have been used to study the fundamentals of sliding friction using a variety of simplified molecular models. [20][21][22][23][24] Sliding friction has been studied using fully atomistic models under conditions of constant surface load or separation, 25,26 or constant chemical potential.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Glycerol Monooleate Confined between Mica Surfaces

Bradley-Shaw

Camp²,

Dowding

et al. 2016

Langmuir

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The structure and frictional properties of glycerol monooleate (GMO) in organic solvents, with and without water impurity, confined and sheared between two mica surfaces are examined using molecular dynamics simulations. The structure of the fluid is characterized in various ways, and the differences between systems with nonaggregated GMO and with preformed GMO reverse micelles are examined. Preformed reverse micelles are metastable under static conditions in all systems. In n-heptane under shear conditions, with or without water, preformed GMO reverse micelles remain intact and adsorb onto one surface or another, becoming surface micelles. In dry toluene, preformed reverse micelles break apart under shear, while in the presence of water, the reverse micelles survive and become surface micelles. In all systems under static and shear conditions, nonaggregated GMO adsorbs onto both surfaces with roughly equal probability. Added water is strongly associated with the GMO, irrespective of shear or the form of the added GMO. In all cases, with increasing shear rate, the GMO molecules flatten on the surface, and the kinetic friction coefficient increases. Under low-shear conditions, the friction is insensitive to the form of the GMO added, whereas the presence of water is found to lead to a small reduction in friction. Under high-shear conditions, the presence of reverse micelles leads to a significant reduction in friction, whereas the presence of water increases the friction in n-heptane and decreases the friction in toluene.

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Molecular dynamics simulations to aid the rational design of organic friction modifiers

Cited by 33 publications

References 22 publications

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

Molecular adsorption, self-assembly, and friction in lubricants

Molecular Dynamics Simulations of Glycerol Monooleate Confined between Mica Surfaces

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