Hydrogels based on physically cross-linked network with high mechanical property and recasting ability

In this work, hydrogels based on polyvinyl alcohol (PVA), acrylamide (AM), calcium chloride, and t-carrageenan were prepared via radical polymerization followed by freezing and thawing process. Comparing with pure PVA hydrogels, the obtained hydrogels possess higher tensile strength (1.54 MPa), Young's modulus (92 kPa), and breaking energy (5.14 MJ/m(3)) due to the synergistic effect of physical cross-linkers containing PVA crystallization, double helix structures of carrageenan and hydrogen bond. Furthermore, the tensile stress of the hydrogel is negligibly changeable after twenty successive loading-unloading tensile tests under different strain demonstrating good fatigue resistance. And the hydrogels can also be recast many times under high temperature, which is favorable for the reuse of materials. Besides, the directional motion of ions endows the hydrogels with electronic conductivity which is very sensitive to the strain deformation. Together with the good mechanical property the hydrogels may have the promising application in flexible sensors.