Theoretical Description of Polyelectrolyte Hydrogel Collapse in Electric Field

Abstract

Theory of collapse of polyelectrolyte hydrogels under the influence of direct electric current is developed. The theory is based on the consideration of the motion of gel-solution boundary. It is shown that this boundary is moving with constant velocity on the first stage of the collapse (some part of hydrogel stayed undeformed). This velocity is theoretically determined by analysis of boundary conditions only (electric current density conservation). It is shown that on the first stage of the process hydrogel collapse caused by direct electric current is described completely by Faraday’s law analog. Hydrogel collapse is described by exponential form of Faraday’s law analog on the second stage. On this stage the whole specimen is deformed. The comparison of proposed theory and results obtained early is carried out. It is shown that the theory is in good accordance with experimental data.