Brownian dynamics study of surface adsorption of a linear polymer in different regimes

Brownian dynamics computer simulations are used to investigate the properties of isolated, terminally attached polymers interacting with a surface. Three regimes of the polymer chains are studied: excluded volume, θ, and self-collapsed. It is found that chains are progressively adsorbed to the surface as the surface attraction is increased. The mean-square radius of gyration power law exponent for excluded volume chains changes from 1.2 (the three-dimensional excluded volume value) to 1.5 (the two-dimensional excluded volume value) when the chains are completely adsorbed and the exponent for the θ chains changes from 1.0 (the three-dimensional θ value) to 1.5 in agreement with previous lattice simulations. The collapsed chain exponent remains at 2/3 throughout the transition. The density profile as a function of the distance from the surface, the asphericity, and computer graphics snapshots of typical configurations reveal more details about the polymer structure. The self-collapsed chain forms a multilayered structure on the surface.