Simulation of Polyethylene Thin Films on a High Coordination Lattice

Abstract

We present the results of some film simulations of polyethylene (PE) on a coarse-grained lattice, which is termed as the second nearest neighbor diamond (2nnd) lattice. Monte Carlo simulations of PE melts have been performed on the 2nnd lattice by including short- and long-range interactions. Films can be obtained from equilibrated bulk snapshots by increasing one periodic side to infinity. The presence of attractive long-range interactions besides the repulsive ones gives a cohesive nature to the film. PE films, which contain up to 108 chains of C99 and have thicknesses of more than 100 A between the two surfaces, can be produced and equilibrated on the 2nnd lattice. In these films, the density profiles are hyperbolic, with end beads being more abundant than the middle beads at the interface. There are orientational preferences at the interface on the scale of individual bonds and whole chains. The center of mass distribution of the chains exhibits oscillatory behavior. A comparison of films with differe...