Dynamics of Polymer Adsorption from Bulk Solution onto Planar Surfaces

Abstract

Polymer adsorption of uncharged homopolymers onto planar surfaces has been investigated by employing a coarse-grained bcad-spring polymer model using simulation techniques. Polymer solutions of two different densities and polymers of two different Contour lengths have been examined. The dynamics of the adsorption process appearing in systems composed of a polymer Solution placed near attractive. but initially polymer-free, surfaces were determined by Brownian dynamics simulations and equilibrium properties of corresponding systems by Monte Carlo simulations. The properties of the systems have been analyzed by monitoring the number of adsorbed polymers, bead density profiles, time and frequency of polymer attachments, spatial extension of polymers perpendicular and parallel to the surface, and configurational characteristics. Initially, the polymers diffuse toward the Surfaces, and at shorter distances the attractive Surface potential starts to pull the polymers toward the surface, making them slightly stretched perpendicular to the Surface. Thereafter, the polymers collapse onto the surface with multiple anchoring, and a slower relaxation increasing the extension of the polymers parallel to the Surfaces appears. Finally, at even longer times, and connected to the slow relaxation of the number of adsorbed polymers, the extension of the polymer coils parallel to the Surface is reduced. and the perpendicular extension is increased, with associated changes of the number of beads residing in tails, loop, and trains. The adsorption process becomes faster at decreasing polymer length and at increasing polymer density. (Less)