Molecular Dynamics on Interface and Nanoscratch Mechanisms of Alkanethiol Self-Assembled Monolayers

Abstract

The interface dynamics and nanoscratched mechanisms of alkanethiol self-assembled monolayers (SAM) chemisorbed on a gold surface are investigated using molecular dynamics simulation. The characteristic mechanisms mainly include the nanoscratched depths, the workpiece temperatures, the scratched speed, the SAM chain lengths, and the shapes of the indenters. The simulation results show that the disorder and the plastic mobility of SAM structures increased with increasing nanoscratched depth. The scratched forces, the potential energy, the friction force, and the friction coefficient increased with increasing scratched depth. The larger scratched depth required a larger force to overcome the resistance, which leads to the increases in the friction force. The variations of the scratched forces and the friction forces after scratching at various temperatures are very similar. An increase in the scratched force, friction force, and friction coefficient with increasing scratched speed is observed. The scratched shape after scratching is clearer for a longer SAM chain. The SAM structures are easily tilted and bent when the chain length is longer. The reaction forces after scratching using a spherical indenter are higher than those after scratching using a Vickers indenter.

Molecular Dynamics Simulation of Conformational Transition and Frictional Performance Modulation of Densely Packed Self-Assembled Monolayers Based on Electrostatic Stimulation

“…37−44 There are also plenty of MD computational contributions emphasizing the detrimental effect of excessive normal load, indentation depth, and scratched speed upon the integrity and function of SAMs. 38,[40][41][42]45,46 Typically, irreversible change and defects of SAM structure, removal of SAM molecules, and loss of function (i.e., lubricating efficiency) occur in these situations.…”

A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

“…In literature, molecular dynamics simulations have been used to study the structural, thermodynamic and mechanical properties of alkane thiol SAM on the gold surface [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Even though, tremendous progress has been achieved both on the experimental and theoretical fronts in understanding the alkane thiol SAM on the gold surface, there are still some challenging areas in this system which need attention, investigation and understanding for the development of applicable devices [37].…”

Mechanical characterization of nanoporous Au modified with self-assembled monolayers

“…SAM-modified surfaces have been applied for biosensing, 12 corrosion inhibition, 13 wetting inhibition, 14 and nanolithography. 15 There have been many studies that have investigated the mechanical properties of SAM-modified Au, [16][17][18][19][20][21] but most of them do not describe the mechanical properties of Au, but SAMs. [16][17][18][19][20] Recently, it was found that plastic deformation of Au occurs more easily in SAM-modified Au films than in unmodified Au films owing to chemomechanical effects.…”

“…15 There have been many studies that have investigated the mechanical properties of SAM-modified Au, [16][17][18][19][20][21] but most of them do not describe the mechanical properties of Au, but SAMs. [16][17][18][19][20] Recently, it was found that plastic deformation of Au occurs more easily in SAM-modified Au films than in unmodified Au films owing to chemomechanical effects. 21 In the present work, the mechanical properties of nanoporous Au modified by SAMs were investigated using hardness tests.…”