KINETICS OF POLYELECTROLYTE NETWORK SWELLING AND COLLAPSE - EFFECT OFION ASSOCIATION-DISSOCIATION

A theory of kinetics of swelling and collapse of a polyelectrolyte net work is proposed. In addition to the conventional kinetic equation for polyelectrolyte network swelling, the variation of the concentration of freely moving counter ions in the course of network swelling due to the dissociation-association reaction is taken into account. The thre e regimes of collapse of a polyelectrolyte network are distinguished. The first regime is slow deswelling which proceeds at an almost consta nt rate. The second is the short-term regime of fast deswelling at an extremely high rate. In the third regime, the collapse of the polymer network occurs at an almost constant rate, which is even lower than th e rate of initial deswelling. Under some conditions the swelling/deswe lling of a polyelectrolyte network exhibits hysteresis, when the colla pse of a polymer network to the globule state occurs at a better solve nt quality than the globule-coil transition. (C) 1998 Elsevier Science Ltd. All rights reserved.