Associating polyelectrolyte solutions: Normal and anomalous reversible gelation

An equilibrium mean-field theory for dilute polyelectrolyte solution with m any associating groups per chain is presented. We have shown that in additi on to physical gel formation, the aggregation of polyelectrolyte chains in dilute solution can lead to the formation of optimum size clusters. The phy sical reason for the stabilization of such clusters is discussed. Intramole cular optimum cluster formation (necklace conformation) becomes possible fo r long or charged enough chains. The study of influence of the number of st ickers on phase behavior of associating polyelectrolyte solution enabled us to predict a rather unusual counterintuitive effect: The physical gel form ation can be induced by the decrease of the number of stickers (anomalous p hysical gelation). This effect has pure polyelectrolyte nature and is conne cted with the translational entropy of mobile counterions. (C) 2001 America n Institute of Physics.