Transparent, self-healable, shape memory poly(vinyl alcohol)/ionic liquid difunctional hydrogels assembled spontaneously from polymer solution

Self-healable, shape memory poly(vinyl alcohol) (PVA)/ionic liquid (PVA/IL) hydrogels were assembled from poly(vinyl alcohol) and 1-butyl-3-methylimidazolium tetrafluoroborate solutions by a one-step strategy at room temperature. The gelation was due to the judicious design of   the supermolecular interactions between PVA and IL, including electrostatic   interactions and hydrogen bonding. Differential scanning calorimetry and tensile tests etc. were applied to study the effect of IL on the hydrogels. The results showed that the optimum thermal and mechanical properties of the hydrogel are obtained with higher IL content. The tensile strength and elongation at break of PVA/IL-1.00 hydrogel were 1.447 MPa and 750%, respectively. The self-healing efficiency reached up to 92.60%. Due to the reversible metal ion cooperation in ferric sulfate and the reduction of Fe 3+ in ascorbic acid, the hydrogels exhibited a redox-stimulated shape memory effect. The cytotoxicity test indicated the promising applications for biomedical materials including artificial   skin and wound   dressings.