Dynamic study of single-chain adsorption and desorption

The dynamics of adsorption and desorption of uncharged homopolymers have been investigated using a coarse-grained model comprised of a bead-spring chain and a planar surface. Brownian dynamics simulation has been used to examine the adsorption process for polymers released near the surface and with bulk properties as well as Monte Carlo simulations to explore equilibrium adsorption structures of the polymer. Systems with varying polymer contour length, polymer stiffness, and polymer-surface interaction potential have been considered. Investigations have been made on polymer extensions perpendicular and parallel to the surface and also characterized the adsorbed state in terms of loops, tails, and trains. After a diffusion of the polymer to the vicinity of the surface, three succeeding phases were identified: distortion, attachment, and relaxation phase. In the distortion phase, the polymer starts to experience the potential of the surface and becomes elongated perpendicular to the surface. In the attachment phase, the polymer makes direct contact with the surface and becomes contracted perpendicular to the surface and starts to spread on the surface. Finally, in the extended relaxation phase, the polymer continues to spread on the surface