Inverted critical adsorption of polyelectrolytes in confinement
Abstract
What are the fundamental laws for the adsorption of charged polymers onto oppositely charged surfaces, for convex, planar, and concave geometries? This question is at the heart of surface coating applications, various complex formation phenomena, as well as in the context of cellular and viral biophysics. It has been a longstanding challenge in theoretical polymer physics; for realistic systems the quantitative understanding is however often achievable only by computer simulations. In this study, we present the findings of such extensive MonteCarlo in silico experiments for polymersurface adsorption in confined domains. We study the inverted critical adsorption of finitelength polyelectrolytes in three fundamental geometries: planar slit, cylindrical pore, and spherical cavity. The scaling relations extracted from simulations for the critical surface charge density $\sigma_c$defining the adsorptiondesorption transitionare in excellent agreement with our analytical calculations based on the groundstate analysis of the Edwards equation. In particular, we confirm the magnitude and scaling of $\sigma_c$ for the concave interfaces versus the Debye screening length $1/\kappa$ and the extent of confinement $a$ for these three interfaces for small $\kappa a$ values. For large $\kappa a$ the critical adsorption condition approaches the planar limit. The transition between the two regimes takes place when the radius of surface curvature or half of the slit thickness $a$ is of the order of $1/\kappa$. We also rationalize how $\sigma_c(\kappa)$ gets modified for semiflexible versus flexible chains under external confinement. We examine the implications of the chain length onto critical adsorptionthe effect often hard to tackle theoreticallyputting an emphasis on polymers inside attractive spherical cavities.
 Publication:

Soft Matter
 Pub Date:
 2015
 DOI:
 10.1039/C5SM00635J
 arXiv:
 arXiv:1503.02040
 Bibcode:
 2015SMat...11.4430D
 Keywords:

 Condensed Matter  Soft Condensed Matter;
 Physics  Biological Physics
 EPrint:
 12 pages, 10 figures, RevTeX