Dynamics of polymer adsorption from dilute solution in shear flow near a planar wall

Abstract

Adsorption of polymers from dilute solution subject to shear flow near a planar wall is studied using kinetic theory. A dumbbell model consisting of two beads connected by a nonlinear spring is used to describe the polymer molecules, and the beads interact with the wall via a short-range exponential potential. Bead-bead and bead-wall hydrodynamic interactions are also included in the theory. For an initially bare surface, it is found that the quantity of polymer adsorbed decreases with an increase in polymer molecular weight at a given shear rate and point in time. In addition, for a given molecular weight and point in time, the quantity adsorbed decreases with an increase in shear rate. When adsorbed polymer is initially present, similar trends are observed. Furthermore, complete desorption can be achieved at a sufficiently high shear rate. In all cases, the time required to approach a steady value of the adsorbed amount is many orders of magnitude larger than the dumbbell relaxation time. The above findings are in qualitative agreement with experimental measurements reported nearly three decades ago by Lee and Fuller [J. Colloid Interface Sci. 103, 569 (1985)]. Our findings also suggest that the physical mechanism underlying the long-standing observation that shear flow inhibits polymer adsorption and assists polymer desorption is hydrodynamic interaction between stretched polymer molecules and the adsorbing surface.

Effects of polymer adsorption on the effective viscosity in microchannel flows: phenomenological slip layer model from molecular simulations

“…Figure 8 (lower left) confirms that this algebraic functionality with W i fits the adsorbed density well with an asymptote f for high Weissenberg number. A similar decrease with W i was found by Dutta and co-workers using kinetic theory [15], although their results had f = 0. The Péclet number can now be written…”

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Coarse-Grain Modeling of Shear-Induced Binding between von Willebrand Factor and Collagen

“…They concluded shear flow causes molecular migration leading to desorption. Increase in the flow strength resulted in a decrease in the quantity adsorbed and the film thickness (19,20). Radtke and Netz (21) investigated adsorption behavior of collapsed homopolymers on different surface models.…”

Suppressing the Rebound of Impacting Droplets from Solvophobic Surfaces by Polymer Additives: Polymer Adsorption and Molecular Mechanisms

“…are known not to be universal but to depend strongly on many factors including the shear rate, the polymer concentration, the polymer length, and the polymer-surface attraction strength. 39,40 Under our specific condition, n ads increases during both the spreading and retraction stages, and it starts to decrease at the beginning of the hopping stage. We define n ads at the beginning of the hopping (where v axial in Figure 3(c) is maximum) as n ads,hop to characterize the polymer contribution to the anti-rebound.…”