| 초록 |
The behavior of polyelectrolyte solutions at surfaces is studied using Monte Carlo simulation and density functional theory (DFT). A primitive model of the solution is considered, where the solvent is a dielectric continuum, the polymers are a string of charged beads, the surface is smooth and uniformly charged, and the counter-ions and co-ions are charged hard spheres. The simulations show an interesting interplay between electrostatic and excluded volume effects under typical conditions. The thickness of the adsorbed layer decreases with increasing polymer concentration or surface charge density, but the total adsorbed amount displays a non-monotonic dependence on polymer concentration. A simple DFT, where liquid state correlations are neglected, is in qualitative agreement with simulations for the density profiles but fails to capture the layering and charge inversion effects. Incorporating these correlations into the theory provides a quantitatively accurate theory for the structure of polymers at surfaces. The effect of explicit molecular solvent on the adsorption behavior is also discussed. |
