Adsorption of polyelectrolytes at an oppositely charged surface

We develop a scaling theory of polyelectrolyte adsorption at an oppositely charged surface. At low surface charge densities, the thickness of the adso rbed layer is determined by the balance between electrostatic attraction to the charged surface and chain entropy. At high surface charge densities, i t is determined by the balance between electrostatic attraction and short-r ange monomer-monomer repulsion. These different stabilizing mechanisms resu lt in the nonmonotonic dependence of the layer thickness on the surface cha rge density.