Preparation and mechanical properties of a transparent ionic nanocomposite hydrogel

The poor stability of clay dispersion in the presence of ionic species presents a challenge for preparing a transparent ionic nanocomposite (NC) hydrogel with the desired strength. A transparent ionic NC hydrogel was successfully prepared by in situ copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylamide (AAm) in the Laponite dispersion. AMPS played a dominant role in the dispersion of Laponite. Mechanical analyses demonstrated that this type of hydrogel has a combination of high tensile strength and excellent stretch ability. An increase in AMPS content made a big contribution to the tensibility, while an increase in clay content improved the elastic modulus. The ionic NC hydrogel exhibited a self-healing property, which occurred autonomously, without any outside intervention. The results showed that physical interaction among the NC hydrogels can be recovered. This work is a continuation of our previous efforts on the preparation and application of ionic NC hydrogels, for which there is a range of potential applications in soft and smart machines in the future.