Adsorption of tethered polyelectrolytes onto oppositely charged solid-liquid interfaces

We consider an equilibrium structure of a monolayer formed by weakly charge d polyelectrolyte chains tethered to the oppositely charged interface. The interface is characterized by an immobile charge spatially distributed in a sublayer of finite thickness submerging tethered polyions. The Coulomb att raction of tethered polyions to the surface induces their adsorption. Three complementary theoretical approaches (scaling, analytical self-consistent- field approach, and numerical self-consistent-field model) are put to the p roblem in order to provide a complete description of the behavior of this c omplex charged interface. Both the value of the charge immobilized at the s urface and the ionic strength of the solution influence the conformations o f grafted polyelectrolytes in a significant way. It is shown that the heigh t of sufficiently densely grafted polyelectrolyte monolayers ("polyelectrol yte brushes") can depend nonmonotonically on the value of the ionic strengt h of the solution. The relevance of the system to help understanding comple x interfaces, as they occur in, e.g., casein micelles, is discussed.