Nucleation Mechanisms of Self-Assembled Physisorbed Monolayers on Graphite

Coarse-grained
molecular dynamics simulations are employed to obtain a detailed view
of the formation of long-range ordered lamellar structures of physisorbed
self-assembling long functionalized alkanes on graphite. During the
self-assembly, two processes take place: Langmuir preferential adsorption
and rearrangement on the surface. The rearrangement starts with nucleation,
in which molecules create an ordered domain. The nucleation mechanism
is temperature dependent. At lower temperature independent, small
and stable nuclei seed the emergence of long-range ordered domains.
In contrast, at a higher temperature, molecules adsorb on the surface,
and only when a certain level of surface coverage by the adsorbent
is reached, the whole structure undergoes a transition from a liquid-like
structure to an ordered structure. After this step, relatively slow
corrections of the structure take place by Ostwald ripening.