Critical adsorption of polyelectrolytes onto planar and convex highly charged surfaces: the nonlinear Poisson–Boltzmann approach

Abstract

We study the adsorption-desorption transition of polyelectrolyte chains onto planar, cylindrical and spherical surfaces with arbitrarily high surface charge densities by massive Monte Carlo computer simulations. We examine in detail how the well known scaling relations for the threshold transitiondemarcating the adsorbed and desorbed domains of a polyelectrolyte near weakly charged surfacesare altered for highly charged interfaces. In virtue of high surface potentials and large surface charge densities, the Debye-Hückel approximation is often not feasible and the nonlinear Poisson-Boltzmann approach should be implemented. At low salt conditions, for instance, the electrostatic potential from the nonlinear Poisson-Boltzmann equation is smaller than the Debye-Hückel result, such that the required critical surface charge density for polyelectrolyte adsorption s c increases. The nonlinear relation between the surface charge density and electrostatic potential leads to a sharply increasing critical surface charge density with growing ionic strength, imposing an additional limit to the critical salt concentration above which no polyelectrolyte adsorption occurs at all. We contrast our simulations findings with the known scaling results for weak critical polyelectrolyte adsorption onto oppositely charged surfaces for the three standard geometries. Finally, we discuss some applications of our results for some physical-chemical and biophysical systems.

Analysis and spline approximation of surface charge and potential at planar electrochemical interfaces

“…It appears in connection with a wide range of applications and the topic has received increasing attention in recent years. 7,30,31 In this lines, a particularly important case concerns the adsorption of polyelectrolyte chains onto surfaces with a low-dielectric constant. Such a case occurs, eg, when the charged surface is given by a biological membrane, a polymer latex surface or a globular protein.…”

“…Such an equation is nothing more than a continuum mean-field type approximation for the charge density of the electrolyte ions, assuming thermodynamic equilibrium, point-like ions and neglecting statistical correlations. [6][7][8][9][10] However, despite its simplicity and effectiveness, the assumptions used do not always occur in practice. 11,12 To overcome this difficulty, alternative mean-field type models that take into account, for instance, finite-size ions to include absorption effects onto the charged surface, have been proposed, 6,[13][14][15] giving rise to the so-called modified Poisson-Boltzmann theory.…”

“…Electrostatic interactions between charged surfaces and mobile ions within an electrolyte solution are usually addressed by studying the Poisson‐Boltzmann equation. Such an equation is nothing more than a continuum mean‐field type approximation for the charge density of the electrolyte ions, assuming thermodynamic equilibrium, point‐like ions and neglecting statistical correlations . However, despite its simplicity and effectiveness, the assumptions used do not always occur in practice .…”

The interplay of nanointerface curvature and calcium binding in weak polyelectrolyte-coated nanoparticles

“…Extensive computer simulations have been recently performed studying the adsorption of PA chains onto charged surfaces. 58,59 In such scenarios, the molecular theory can provide a deeper molecular understanding of the interactions between polyelectrolytes in multivalent ions solutions, which is fundamental for a rational design of nanomaterials with applications in biological environments.…”

Conformational properties of block-polyampholytes adsorbed on charged cylindrical surfaces

“…There are a number of theoretical studies addressing the conditions in which the polyelectrolytes-surface intera e-mail: sidneyjc@ibilce.unesp.br action is strong enough to get adsorption as well as the conformational states of the adsorbed chain [10,[29][30][31][32][33][34][35][36][37][38][39][40][41][42]. In particular, the adsorption of a single random polyampholyte chain on a flat charged surface was addressed theoretically by Dobrynin and co-authors [43].…”