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

Zheng, Xuan; Zhu, Hong Tao; Chen, Kuiyu

doi:10.1504/ijsurfse.2014.060491

Cited by 8 publications

(8 citation statements)

References 26 publications

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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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Section: Introductionmentioning

confidence: 99%

Molecular adsorption, self-assembly, and friction in lubricants

Apóstolo

Tsagkaropoulou

Camp

2019

Journal of Molecular Liquids

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“…The C4-alkane is simulated by the TraPPE United Atom force field which utilizes pseudo-atoms to represent the CHx groups [43]. It should be noted that, TraPPE United Atom for field is not the best one to accurately describe the material properties compared to other advanced force fields, but it is still widely used from the consideration of computational efficiency [25][26][27][43][44][45]. Thus, we have applied the TraPPE United Atom force filed for atomistic simulations in order to reduce the computational cost, which is very important for NEMD simulations when there are a huge number of cases to run.…”

Section: Force Fieldmentioning

confidence: 99%

“…To date, several simulations based on the molecular dynamics method have been conducted to investigate surface contact and the frictional characteristics of various lubricants and nanoparticles. There are models including single asperity [21], amorphous [22] or 2D rough surface [23], 3D rough surface contact [24], thin film model with flat surface [25] and 3D rough surface [26,27]. It should be pointed out that all these above-mentioned simulations with sliding walls are nonequilibrium molecular dynamics (NEMD) simulations in tribology [28].…”

Section: Introductionmentioning

confidence: 99%

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Study on Lubrication Characteristics of C4-Alkane and Nanoparticle during Boundary Friction by Molecular Dynamics Simulation

Zheng

Deng

et al. 2021

Metals

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Lubricant has been widely applied to reduce wear and friction between the contact surfaces when they are in relative motion. In the current study, a nonequilibrium molecular dynamics (NEMD) simulation was specifically established to conduct a comprehensive investigation on the dynamic contact between two iron surfaces in a boundary friction system considering the mixed C4-alkane and nanoparticles as lubricant. The main research objective was to explore the effects of fluid and nanoparticles addition on the surface contact and friction force. It was found that nanoparticles acted like ball bearings between the contact surfaces, leading to a change of sliding friction mode to rolling friction mode. Under normal loads, plastic deformation occurred at the top surface because nanoparticles were mainly supporting the normal load. By increasing the number of C4-alkane molecules between two contact surfaces, the contact condition has been changed from partial to full lubrication. In addition, an attractive force from the solid–liquid LJ interaction between C4-alkane and surfaces was observed at the early stage of sliding, due to the large space formed by wall surfaces and nanoparticles. The findings in this paper would be beneficial for understanding the frictional behavior of a simple lubricant with or without nanoparticles addition in a small confinement.

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“…Atomistic molecular simulations have been used to study the frictional properties of a very wide range of molecular systems, 17 including polymers and hydrocarbons, [18][19][20][21][22][23][24] silanes, 25 fatty acids and amines, [26][27][28][29][30][31][32] glycerin, 33 glycerides, 34 zinc dialkyldithiophosphates, 35 molybdenum sulfides, 36,37 room-temperature ionic liquids, 38,39 and carbon nanoparticles. 40 In very recent work, Ewen et al carried out a comprehensive survey of various organic friction modifiers adsorbed on iron oxide surfaces, and lubricated by a very thin film of hexadecane.…”

Section: Introductionmentioning

confidence: 99%

Self-assembly and friction of glycerol monooleate and its hydrolysis products in bulk and confined non-aqueous solvents

Bradley-Shaw

Camp

Dowding

et al. 2018

Phys. Chem. Chem. Phys.

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Atomistic molecular dynamics simulations are used to study the self-assembly and friction of glycerol monooleate mixed with oleic acid, glycerol, calcium oleate, or water in n-heptane and toluene solvents. The aim is to determine how chemical degradation products of glycerol monooleate could lead to changes in structural and frictional properties. In bulk solution, almost all mixtures studied contain self-assembled reverse micelles. Under confinement between sheared mica surfaces, the reverse micelles disintegrate, but the distribution of molecules between the surfaces and the centre of the fluid layer depends sensitively on the chemical composition, with more polar mixtures showing stronger adsorption. The measured kinetic friction coefficient is correlated with the extent of surface adsorption: while degradation products lead to increases in the friction coefficient in most cases, all changes are more pronounced when there is less surface adsorption.

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

Cited by 8 publications

References 26 publications

Molecular adsorption, self-assembly, and friction in lubricants

Molecular adsorption, self-assembly, and friction in lubricants

Study on Lubrication Characteristics of C4-Alkane and Nanoparticle during Boundary Friction by Molecular Dynamics Simulation

Self-assembly and friction of glycerol monooleate and its hydrolysis products in bulk and confined non-aqueous solvents

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