  We explore the mechanical response of a single polyelectrolyte chain under
tension in good and poor solvents using a combination of simulation and theory.
In poor solvents, where the equilibrium state of the chain is a collapsed
globule, we find that the chain undergoes a globule-coil transition, as the
magnitude of the force is increased beyond a critical value. This transition,
where the polymer size changes discontinuously from a small to a large value,
is accompanied by release of bound counterions from the chain. We explain these
results by adhering to a statistical mechanical theory of counter-ion
condensation on flexible polyelectrolytes.
