Polyelectrolytes: On the doorsteps of the second century

Polyelectrolytes are macromolecules with ionizable groups. In this perspective, I will present a brief history of polyelectrolytes starting from the seminal papers published in the first half of the 20th century followed by the current developments in the field and by the list of the standing problems. Particular emphasis will be on how static and dynamic properties of polyelectrolyte solutions depend on the fraction of dissociated ionic groups, solvent quality for the polymer backbone, and salt and polymer concentrations.