Shapes of strongly absorbed polyelectrolytes in poor solvents

The pearl necklace instability has been predicted to occur for single polyelectrolyte chains immersed in an incompatible (or poor) solvent, but still direct imaging of this chain conformation is not conclusive. We therefore examine how a surface may interact with the polyelectrolyte to, possibly, inhibit this instability. We show from explicit calculations that for strongly absorbed polyelectrolyte chains another conformation of the chain is stable in parts of the diagram of states. We support this calculation with more rigorous numerical, self-consistent mean field calculations which exhibit both elliptical globules and a pseudo pearl necklace structure.