Some Thoughts On Polyelectrolyte Persistence Length

Electrically charged, intrinsically flexible polymers in low ionic strength aqueous solutions are known to be stretched in order to reduce the Coulomb self-energy. As the solution ionic strength increases with added salt, Debye screening weakens the repulsion between distant parts of the chain and the polymer is envisioned as a semi-flexible chain with a persistence length that is governed by the Debye screening length. However for nearly fifty years, the dependence of this electrostatic persistence length on ionic strength has been controversial. This presentation will discuss recent experiments and theoretical thoughts that might contribute to unraveling this dilemma.