Investigation of the Impact of Cross-Polymerization on the Structural and Frictional Properties of Alkylsilane Monolayers Using Molecular Simulation

Abstract

Cross-linked chemisorbed n-alkylsilane (CH3(CH2)n−1Si(OH)3) monolayers on amorphous silica surfaces have been studied and their structural properties and frictional performance were compared to those of equivalent monolayers without cross-linkages. The simulations isolated for the first time the effects of both siloxane cross-linkages and the fraction of chains chemisorbed to the surface, providing insight into a longstanding fundamental question in the literature regarding molecular-level structure. The results demonstrate that both cross-linkages and the fraction of chemisorbed chains affect monolayer structure in small but measurable ways, particularly for monolayers constructed from short chains; however, these changes do not appear to have a significant impact on frictional performance.

Arrangement of Monofunctional Silane Molecules on Silica Surfaces: Influence of Alkyl Chain Length, Head-Group Charge, and Surface Coverage, from Molecular Dynamics Simulations, X-ray Photoelectron Spectroscopy, and Fourier Transform Infrared Spectroscopy

“…However, only few MD simulations studies have addressed these questions. Different MD studies suggested that the order parameter of n -alkylsilane monolayers (for n > 8) increases as the alkyl chain length and the surface coverage increase, while alkyl chain tilt angles are independent of chain length and decrease as surface coverage increases. − Among them, it was also shown that perfluorodecyltrichlorosilane (FDTS) monolayers at high surface coverage present a hexagonal packing, whereas such packing was attenuated for octadecyltrichlorosilane (OTS) monolayers for the same surface coverage . In the present study, we demonstrate an effect of the head-group charge and alkyl chain length ( n < 18), on the organization of the monolayer.…”

Non-monotonic variation of flow strength in nanochannels grafted with end-charged polyelectrolyte layers

“…Although the enhancement of the electrokinetic transport over concentrated brush-like PELs has not been validated by experimental measurements, it is well known that high packing densities are crucial for the tribological performance of monolayers. 71–73 Our theoretical work suggests that densely packed monolayers can enhance electrokinetic transport and encourages further experimental studies.…”

Experimental Investigation and Molecular Dynamics Simulation on the Anti-Adhesion Behavior of Alkanethiols on Nickel Insert in Micro Injection Molding

“…According to the experimental results, the atomic models of self-assembled molecules on the insert surface were built. The adsorption behaviors of different interfaces were investigated by MD method [ 23 , 24 , 25 ]. Moreover, the anti-adhesion mechanisms of the polymer-alkanethiols interface in different arrangements were explored by analyzing the morphological evolution, potential energy, interaction energy, adhesion work and the radial distribution function at the interface comprehensively.…”