Polyelectrolyte hydrogels are networks consisting of charged macromolecules that are either chemically or physically cross-linked. One notable property of hydrogels is their significant swelling in water, which happens due to the osmotic pressure exerted by the confined counterions and the self-repulsion of the charged chains. The expansion of a hydrogel is counteracted by the elastic restoring force arising from the entropic and energetic elasticity of the polymer chains. When these two forces balance, a swelling equilibrium with a characteristic equilibrium size results. Ionic hydrogels have the ability to alter their conformation and, therefore, their equilibrium size in response to external stimuli such as changes in the ionic strength and the pH, 7,8 making them useful in various technological applications such as oil recovery, artificial muscles and desalination.