Steered molecular dynamics simulation of elastic behavior of adsorbed single polyethylene chains

We investigate the dynamics of the detachment of single polyethylene (PE) chains from a strongly adsorbing surface in vacuum using a united atom model. Various statistical properties, including the mean-square end-to-end distance < R-2 >, the mean-square radii of gyration < S-2 >(xy), < S-2 >(z) the shape factor <delta >, the torsion angle distribution, the average surface adsorption energy < E-surface > the average total energy < U >, and the average force < f >, are analyzed. The relationship between the average force < f > and the pulling velocity v shows two distinctive regions: a weakly dependence region at v < 10(-2) angstrom/ps and a strongly dependence region at v > 10(-2) angstrom/ps. Remarkably, the PE chain manifests force hysteresis under sequential stretching and releasing. These investigations may provide some insights into the elastic behavior of adsorbed polymer chains. (c) 2007 Wiley Periodicals, Inc.