Molecular dynamics simulations of friction between ordered organic monolayers

Tomohiro Shiokawa, Takuya Ohzono and Masamichi Fujihira

Department of Biomolecular Engineering, Tokyo Institute of Technology,
4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan

Molecular dynamics (MD) simulation has been used to study friction between two ordered organic monolayers of alkane chains bound at their ends to rigid substrates. We have modeled films of close-packed hydrocarbon chains of six units long. The experimental monolayers, however, may consist of longer molecular chains. With the increase in the treated atoms, the size of calculation for the MD simulations will be enormously large. In this work, an upper film that has only methyl groups with the same 2D lattice constant as that of a lower film was introduced. The observed average friction force on such a model was found to be about a half of that observed with the previous model. The temperature evolution also showed the same tendency as the previous one.