Effect of water on structural and frictional properties of self assembled monolayers.

Self-assembled monolayers (SAMs) of n-alkanethiols [(CH3(CH2)(n-1), n = 14, 15] on Au(111) in the presence of water have been simulated by molecular dynamics simulation. The behavior and effects of compression on structural characteristics and water penetration into monolayers under different ranges of normal pressures have been investigated. Frictional properties of hydrated SAM systems under various sliding velocities, and loading conditions are examined to explore correlation between the amount of water penetration and friction.

Frictional properties of two alkanethiol self assembled monolayers in sliding contact: odd-even effects.

Using molecular dynamics simulation, we have investigated the structural effects on the frictional properties of self assembled monolayers (SAM) of n-alkanethiols [CH(3)(CH(2))(n-1)SH, n = 12-15] in SAM-SAM contacts attached on Au (111) substrates. We have observed an odd-even effect where friction coefficient for SAM-SAM contacts with n = odd showed consistently higher values than those with n = even. This odd-even effect is independent of the sliding velocity and the relative tilt directions of the SAMs, and persists over a much higher pressure range than that reported before for SAM-Au contacts [L.

Effect of load on structural and frictional properties of alkanethiol self-assembled monolayers on gold: some odd-even effects.

We have conducted molecular dynamics simulations to study the frictional properties of alkanethiols CH(3)(CH(2))(n-1)SH (Cn, 12 ≤ n ≤ 15) self-assembled monolayers (SAMs) on Au(111) surfaces, under various loading and shearing conditions. For the examined alkanethiols, we found some evidence of the friction coefficient being dependent on the number of carbon atoms in the molecule being odd or even. Alkanethiols with n = odd show consistently higher friction coefficients than those with n = even.

Odd-even effects on the structure, stability, and phase transition of alkanethiol self-assembled monolayers.

Molecular dynamics simulations were conducted to predict the structural properties and phase transition temperatures of n-alkanethiols CH(3)(CH(2))(n-1)SH (Cn, 4 ≤ n ≤ 22) self-assembled monolayers (SAMs) on Au (111) surfaces. We studied the effects of chain length on the structural properties, including tilt and orientation angles, and on phase transition temperature. We found clear dependence of the structural properties, on both the number of carbon atoms, n; and on n being odd or even.