Unimpaired highly extensible tough chemically crosslinked hydrogel after experiencing freeze/thaw and boiling processes

Abstract A highly extensible, tough, chemically crosslinked double‐network (DN) hydrogel was synthesized from acrylamide. Three samples of this hydrogel were swelled using different solutions. One swelled in water, one in an aqueous glycerol solution, and one in an aqueous sodium chloride solution. The freezing points of the hydrogel samples were determined using differential scanning calorimetry (DSC). Then, the samples underwent controlled freeze–thaw cycles, and their mechanical behavior under loading‐unloading‐reloading large‐strain tensile deformation were analyzed. The results of these mechanical tests indicated that all the data points for deformation cycles coincided, despite the large water content of the samples. This means that no mechanical damage occurred during the deformation process. The results of hydrogel samples boiled in these solutions also showed no damage. Thus, it can be concluded that the tough chemically crosslinked DN hydrogel does not damage under large‐strain tensile deformations even after experiencing harsh environmental conditions, such as freeze/thaw or boiling processes, which makes it a great candidate for applications that involve large temperature variations. The resistance of the DN hydrogel to damage is attributed to the specific molecular architecture of this hydrogel, in that the building block of this material is a loosely crosslinked polymeric network.