Is the counterion condensation point on polyelectrolytes a trigger of structural transition?

Experimental data on well documented global polymer transitions can be correlated with the linear charge density critical for counterion condensation. Other data exhibit abrupt behavior at the counterion condensation point and may consistently be interpreted in terms of a transition between locally folded and extended structures. We suggest that the underlying cause of these observations is the onset of mechanical instability of locally folded structures at the counterion condensation point.