I. E. Suleimenov

Concentration redistribution of low-molecular-weight salts of metals in the presence of a strongly swelling polyelectrolyte hydrogel

Abstract This paper deals with the behaviour of a superswelling hydrogel based on sodium polyacrylate crosslinked with the allyl ester of carboxymethyl cellulose in solutions of salts of mono- and polyvalent metals. The effect of cooperative sorption of polyvalent ions by the hydrogel was detected. An expression describing the concentration redistribution in the system hydrogel-univalent salt solution was obtained.

Peculiarities of the kinetics of polyelectrolyte hydrogel collapse in solutions of copper sulfate

Abstract The kinetics of polyelectrolyte hydrogel collapse in water solutions of CuSO4 was studied. It was shown that the equilibrium degree of contraction essentially depends on the route by which the equilibrium is attained. The hydrogel kinetics of collapse in solutions of polyvalent metal salts is interpreted from the point of view of two different mechanisms of gel collapse. The transition from one mechanism to the other one is determined by the time of hydrogel interaction with the salt solution and by its concentration.

Swelling behaviour of a polyelectrolyte network under load

Abstract The kinetics of swelling of a strongly charged hydrogel is studied. The influence of external load on the rate of swelling and on the equilibrium degree of swelling is experimentally investigated. With the help of a sensitive technique it is shown that two different mechanisms governing the process of swelling may be clearly determined. The first one (at the beginning of swelling) is connected with the ‘ordinary’ swelling of a neutral network, and the second one corresponds to the largest part of the kinetic curve and is connected with additional electrostatic interactions. The dynamics of hydrogel swelling, which corresponds 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 equations. It allows one to obtain a correlation between static and dynamic parameters of the swelling process and the dependence of these parameters on applied load.