Structure of α-Olefins on Different Solid Surfaces: A Molecular Dynamics Study

Molecular dynamics simulations of different alpha-olefin molecules on different solid surfaces, aluminum, graphite, and silicon dioxide (SiO2) were carried out. Then, studies of how alpha-olefins were adsorbed on the different surfaces were conducted in terms of density profiles and angular distributions of the molecules chains. It was found that depending on the solid surface the molecules arrayed in different ways. On the aluminum surface the olefin molecules formed a well-defined layer, next to the wall, adsorbed by the double bond with their tails perpendicular to the surface. On the other hand, the alpha-olefin molecules close to graphite and SiO2 surfaces were adsorbed with their chains parallel to the interfaces. Structure of the molecules, next to the surfaces, was also investigated by analyzing pair correlation functions and an order parameter finding that the molecules present a strong structure on the aluminum surface. Finally, the molecule-surface description given by the two potentials was compared, and different structures were observed on the aluminum surface. Since the results obtained with the Buckingham interaction were considered as the correct, then we found the appropriate Lennard-Jones parameters to reproduce similar data to those given by the Buckingham potential.