A body temperature and water-induced shape memory hydrogel with excellent mechanical properties

Shape memory hydrogels with capacity of shape deformation after being triggered by physiological stimuli have potential to be used in biomedical fields. In this study, a body temperature and water-responsive shape memory hydrogel with excellent mechanical properties was prepared by crosslinking dopamine-terminated tetra-poly(ethylene glycol) (4-arm PEG) with an oxidation reaction. By adjusting the water content of hydrogels, the temperature/water responsivity and the mechanical properties could be well controlled. Under the synergistic effect of body temperature and water stimulation, the hydrogels can achieve fast shape recovery with a recovery time of 1 min 14 s, and a recovery ratio of 98.9%. Tensile tests reveal that the gel has good mechanical properties. The tensile fracture strength can reach the megapascal level ranging from 2.68 to 13.02 MPa, and the elongation at break can reach 2501%. The integration of body temperature and water-induced shape memory properties and mechanical properties will broaden the application of the 4-arm PEG hydrogel in the biomedical field.