Effect of the polymer network on the diffusion of foreign particles in hydrogels

Abstract

In the present work, we introduce a physical model of foreign particle diffusion in polymer hydrogels that accounts for the network architecture of these systems. The model employs a classical diffusion theory framework in condensed media to derive a theoretical dependence of the diffusion coefficient on the volume occupied by the hydrogel’s network. We demonstrate that the changes in the diffusion of foreign particles can be attributed to the changes in the free activation energy due to the presence of the polymer network. Using optical image analysis, we obtained the dependence of the diffusion coefficient in agarose and gelatine hydrogels on the concentration of the gelling agent. The experimental data obtained are in good agreement with the theoretical dependences predicted by the proposed physical model. Furthermore, when the size of the diffusing particles is much smaller than the hydrogel pore size, the diffusion coefficient appears to be independent of the nature of the hydrogel and determined solely by the gelling agent concentration.