ABSTRACT
The capability of the hydrogels to absorb a large amount of water makes them similar to highly viscous solutions and is the basis of the thixotropic behavior that characterizes some of them. Thixotropy is defined as the behavior of certain materials which appear as solid, but under great stress become liquid. When the stress is removed the material settles back into its original consistency, i.e. solid. This transformation from solid to liquid and vice versa does not affect the chemistry of the hydrogel even if determinates a change in its overall structure. An explanation of the behavior of thixotropic hydrogel is discussed together with the mechanical and physico-chemical analysis necessary to check up the thixotropic nature. Among the several examples of thixotropic materials, interpenetrating hydrogels and hybrid hydrogels with magnetic nanoparticles are discussed.
