  In this paper we analyze the behavior of hydrophobic polyelectrolytes. It has
been proposed that this system adopts a pearl-necklace structure reminiscent of
the Rayleigh instability of a charged droplet. Using a Poisson-Boltzmann
approach, we calculate the counterion distribution around a given pearl
assuming the latter to be penetrable for the counterions. This allows us to
calculate the effective electric charge of the pearl as a function of the
chemical charge. Our predictions are in very good agreement with the recent
experimental measurements of the effective charge by Essafi et al. (Europhys.
Lett. 71, 938 (2005)). Our results allow to understand the large deviation from
the Manning law observed in these experiments.
