Stimuli-responsive hydrogels are polymer gels possessing the ability to absorb or release solvent, resulting in a respective change of volume. This volume change can be triggered by applying a chemical or electrical stimulus to the gels placed in a solution bath.
To describe the chemo-electro-mechanical behavior of these hydrogels in the framework of the Theory of Porous Media, they have to be subdivided in a solid phase, fluid phase and an ionic phase. In this theory, the interaction of the different phases is directly incorporated. Due to the complexity of both, the material and the model, a large amount of material parameters is essential. The determination of these parameters is a challenging task. In this investigation, also the interaction between hydrogel (solid and fluid phase) and surrounding solution bath has to be considered in order to determine the viscoelastic behavior of the gel.
Hence, in the present work, polyelectrolyte hydrogels are investigated in consideration of the mechanical characteristics via a tensile test. In the experimental setup the stress is determined by a force sensor and the deformation is analyzed by using a gray scale correlation. Due to the fact, that the mechanical behavior of such multiphasic materials depends on the solid-fluid ratio, the gel is investigated under different swelling degrees. The acquired data then can be used to enhance the material equations. So, an enhanced prediction towards possible applications is gained.