Structure and Dynamics of Surfactant and Hydrocarbon Aggregates on Graphite: A Molecular Dynamics Simulation Study

Maria Sammalkorpi, Athanassios Z. Panagiotopoulos, Mikko Haataja

Tutkimustuotos: LehtiartikkeliArticleScientificvertaisarvioitu

Abstrakti

We have examined the structure and dynamics of sodium dodecyl sulfate (SDS) and dodecane (C12) molecular aggregates at varying surface coverages on the basal plane of graphite via classical molecular dynamics simulations. Our results suggest that graphite−hydrocarbon chain interactions favor specific molecular orientations at the single-molecule level via alignment of the tail along the crystallographic directions. This orientational bias is reduced greatly upon increasing the surface coverage for both molecules due to intermolecular interactions, leading to very weak bias at intermediate surface coverages. Interestingly, for complete monolayers, we find a re-emergent orientational bias. Furthermore, by comparing the SDS behavior with C12, we demonstrate that the charged head group plays a key role in the aggregate structures:  SDS molecules display a tendency to form linear file-like aggregates while C12 forms tightly bound planar ones. The observed orientational bias for SDS molecules is in agreement with experimental observations of hemimicelle orientation and provides support for the belief that an initial oriented layer governs the orientation of hemimicellar aggregates.
AlkuperäiskieliEnglanti
Sivut2915-2921
JulkaisuJournal of Physical Chemistry B
Vuosikerta112
DOI - pysyväislinkit
TilaJulkaistu - 2008
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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