Dynamics of Competitive Polymer Adsorption onto Planar Surfaces in Good Solvent

Abstract

Adsorption of mixed polymer solutions in good solvent containing polymers of different chain length has been studied by applying simulation techniques on a coarse-grained bead-spring polymer model. Fully flexible polymers at varying bead-surface interaction strength and different combinations of flexible, semiflexible, and stiff polymers at a single bead-surface interaction strength have been examined. Monte Carlo simulation techniques have been employed to investigate static equilibrium properties and Brownian dynamic simulations to follow the dynamics of the adsorption process. The properties examined comprise the adsorbed number of polymers, adsorbed number of beads, bead density profiles, components of the polymer radius of gyration, tail, loop, and train configurations, and nematic bond order of adsorbed beads. The adsorption involves an initially independent adsorption of the two polymer types followed by competitive adsorption. The competitive adsorption is characterized by a maximum of the adsorbed amount and a desorption of the polymer with the smallest surface affinity and a continued, but reduced, growth of the adsorbed amount of the polymer with the largest surface affinity. The surface affinity difference between the two polymer types of different length increased with increasing bead-surface interaction. Furthermore, the surface affinity of a polymer initially decreased but then largely increased at increasing stiffness. As a consequence, a stiff short polymer was found to displace a 4-fold longer flexible polymer. The spatial extension of adsorbed polymers as characterized by the radius of gyration parallel and perpendicular to the surface of a polymer of a given flexibility was independent of the flexibility of the other polymer type. The fraction of beads in tails was increased and in trains reduced as the surface affinity of the dissimilar polymer type was raised. Finally, the adsorption layer of a stiff polymer possesses a nematic bond order. In mixed polymer systems, the nematic bond order of a given polymer type manifests a dependence on the flexibility of the other type.

Polyelectrolyte adsorption onto oppositely charged interfaces: unified approach for plane, cylinder, and sphere

“…Several directions for future extensions of the model are apparent. One of them is the consideration of finite-length chains, 40,41 instead of infinitely long PEs, to be able to directly compare the theoretical results with the outcomes of experiments and computer simulations, [42][43][44] see also refs. 45 and 46.…”

MOLSIM: A modular molecular simulation software

“…Polymer networks are usually synthesized by chemically cross-linking charged or titrating polymers. Such gels possess unusual swelling properties and are, for example, used to make soft particles and are used in systems [38,39], b) [40,41], c) [42,43], and d) [44,45]…”

Adsorption of highly charged Gaussian polyelectrolytes onto oppositely charged surfaces

“…Of particular interest is that of adsorption caused by electrostatic forces as many biomolecules like DNA and RNA are highly charged and they frequently bind themselves to oppositely charged protein or membrane surfaces. There is an extensive literature both in theory [7][8][9][10][11][12][13][14][15][16][17] as well as in simulations [18][19][20][21][22][23][24][25][26][27][28][29][30][31] on electrostatic driven adsorption of flexible polyelectrolyte (PE) chains onto surfaces.…”