Strongly charged polymer brushes

We have established phase diagrams for strongly charged polymer brushes as a function of salt concentration n(s), chain grafting density and polymer backbone charge density. We show these are qualitatively different to the previously calculated weakly charged phase diagrams due to electrostatic stiffening and counterion condensation effects, the hallmarks of highly charged polymers such as DNA. Saturated phases arise where chains are locally or globally fully stretched. We show the salt dependence of brush height H depends on the form of the persistence length l(p). In good agreement with experiment, we find H similar to n(s)(-1/3) at higher salt concentrations if a linear relation between lp and Debye length is assumed.