Molecular Dynamics Simulation of the Adsorption and Diffusion of a Single Hydrophobic Polymer Chain on a Hydrophobic Surface

The adsorption and diffusion of polyethylene (PE) with different degrees of polymerization (N) on a silicon (111) surface were studied by molecular dynamics simulations. The relative dielectric constant was selected to be 1 and 78 to mimic a vacuum and a solution environment, respectively. The chains were all present as two-dimensional (2D) adsorption conformation on the surface but different conformations and dynamic properties were found in the two absolutely different environments. This shows that the solvent plays an obvious role in the chain adsorption and diffusion processes on a hydrophobic surface. The relationship between the adsorption energy and the degree of polymerization follows a linear function and the average adsorption energy per segment is -0.38 kJ . mol(-1). In addition, the diffusion coefficient (D) of these chains scales with the degree of polymerization as N-3/2.