The classical molecular dynamics simulations presented here examine the compression and friction of
monolayers composed of linear hydrocarbon chains with 8, 13, or 22 carbon atoms that are chemically
bound (or anchored) to a diamond (111) substrate. The roles structural defects and their formation play
in compression, friction, and energy dissipation processes are examined. The number of defects increases
under increasing load, reaching a plateau at a specified load. Defects are also clearly implicated in the
energy dissipation associated with sliding friction. The friction is found to be highest in shorter chains and
disordered surfaces, in agreement with previous atomic force microscopy studies.
Classical molecular dynamics simulations are used to examine the indentation of monolayers composed of
linear hydrocarbon chains with 8, 13, or 22 carbon atoms that are chemically bound (or anchored) to a diamond
(111) substrate. Indentation is accomplished using both a flexible and rigid single-wall, capped [10,10] nanotube
as the tip. Regardless of the nanotube used, the simulations show that indentation of the hydrocarbon monolayers
causes a disruption of the original ordering of the monolayer, pinning of selected hydrocarbon chains beneath
the tube, and the formation of gauche defects within the monolayer. Because nanotubes are stiff along their
axial direction, the flexible nanotube is distorted only slightly by its interaction with the softer monolayers.
However, interaction with the hard diamond substrate causes the tube to buckle. Severe indents with a rigid
nanotube tip result in rupture of chemical bonds within the hydrocarbon monolayer.
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