Solvent release from highly swollen gels under compression

The behaviour of a strongly charged polyelectrolyte gel under uniaxial compression was studied experimentally, demonstrating gel deformation and solvent loss at the same time. A theoretical interpretation used was based on a thermodynamic approach developed for weakly charged gels. The proposed approach was considered as a first approximation of the solution of the problem on gel volume loss under compression. It predicts solvent release under compression for both weakly charged and neutral gels, being more pronounced for polyelectrolyte hydrogels. A qualitative agreement between experiments and proposed theoretical model was obtained.