(252c) Density Functional Theory for Polyelectrolyte Brushes

Polyelectrolyte brushes have received considerable attention in recent years for its potential applications in colloidal stabilization and in surface protection and lubrication. The strong steric repulsion and electrostatic interactions presented in such systems result in a complicated stretching behavior that have been subjected to numerous experimental and theoretical investigations. In this talk, we present the structural and thermodynamic properties of completely-charged polyelectrolyte brushes predicted by a newly-developed nonlocal density functional theory (NLDFT). By taking into account the counterions and coions explicitly, we examined the effects of salt concentration, counterion valence, surface grafting density, polymer chain length and temperature on the brush swelling behavior and on the local distributions of small ions. For systems containing only monovalent counterions, the theory predicts the brush thickness in good agreement with the scaling law and experimental results.