SWELLING BEHAVIOR OF A POLYELECTROLYTE NETWORK UNDER LOAD

The kinetics of swelling of a strongly charged hydrogel is studied. Th e influence of external load on the rate of swelling and on the equili brium degree of swelling is experimentally investigated. With the help of a sensitive technique it is shown that two different mechanisms go verning the process of swelling may be clearly determined. The first o ne (at the beginning of swelling) is connected with the 'ordinary' swe lling of a neutral network, and the second one corresponds to the larg est part of the kinetic curve and is connected with additional electro static interactions. The dynamics of hydrogel swelling, which correspo nds to strong electrostatic interactions, is analysed by the equation of motion of the hydrogel boundary. The mathematical approach is based on the modern theory of the qualitative solution of differential equa tions. It allows one to obtain a correlation between static and dynami c parameters of the swelling process and the dependence of these param eters on applied load. (C) Elsevier Science Ltd.