Modeling Diffusion of Adsorbed Polymer with Explicit Solvent

Computer simulations of a polymer chain of length N strongly adsorbed at the solid-liquid interface in the presence of explicit solvent are used to delineate the factors affecting the N dependence of the polymer lateral diffusion coefficient, D_∥. We find that surface roughness has a large influence, and D_∥ scales as D_∥∼N^-x, with x≈3/4 and x≈1 for ideal smooth and corrugated surfaces, respectively. The first result is consistent with the hydrodynamics of a “particle” of radius of gyration R_G∼N^ν (ν=0.75) translating parallel to a planar interface, while the second implies that the friction of the adsorbed chains dominates. These results are discussed in the context of recent measurements.