Exploring the Ionic Mechanochemical Coupling Effects in the Swelling Behavior of Hydrogels Based on the Interaction Parameter

Hydrogels, known for their biocompatibility, are crucial in frontier science. Despite their excellent physical and mechanical properties, hydrogels undergo swelling in natural environments, altering their characteristics. This study investigates the ionic mechanochemical coupling effects in the swelling behavior of hydrogels, focusing on the interaction parameter. The Flory-Rehner model, initially proposed for polymer swelling, has been extended to account for ionic mechanochemical effects, which significantly influence hydrogel swelling in salt solutions. This extended model considers the free energy of swelling hydrogels to include network deformation energy, mixing energy, and ion energy, with the effects of ion concentration and reaction on free swelling being an ionic mechanochemical coupling effect. The Flory-Huggins dilute solution theory, scaling theory, reaction kinetics, and Clausius-Mosotti equation are employed to estimate the Flory-Huggins interaction parameters and thermodynamics of hydrogels. The model's effectiveness is verified using experimental results from the literature, demonstrating an understanding of the ionic mechanochemical coupling effects in hydrogel swelling.