Counterion condensation on flexible polyelectrolytes: Dependence on ionic strength and chain concentration

We give a simple scaling picture for dilute and semidilute solutions of fle xible polyelectrolytes including counterion condensation. It is shown that below a critical temperature a fraction of the counterions condenses on the chain. This leads to a renormalization of the total charge of the macroion s as well as to a condensation-induced intrachain attraction resulting in a shrinkage of the chain. The paper extends the scaling picture of Schiessel and Pincus [Macromolecules 1998, 31, 7953] for dilute solutions without ex tra salt to higher ionic strengths and higher chain concentrations. The dia gram of states for the different cases is presented.