Hydrogels are attracting increasing attention due to their potential use in various fields. However, most of the existing hydrogels have limitations in either dissipating mechanical energy or maintaining high stretchability under deformation, thus do not possess high mechanical properties. Herein, poly(vinyl alcohol) (PVA)−tannic acid (TA) hydrogels with both high mechanical strength and stretchability were obtained via a step-by-step physical cross-linking and molecular alignment method. Saline-triggered physical interactions serve as "sacrifice domains" to dissipate energy and endow PVA-based hydrogel with high mechanical strength (≈16 MPa) and stretchability (≈1000%). Due to the reversible arranging and disassociating property of physical interactions, PVA−TA hydrogels show excellent shape memory performance. We further demonstrated an effective approach to fabricate strong and aligned PVA−TA thread. The resultant well-aligned PVA−TA dry thread reveals an ultrahigh mechanical tensile strength of up to 750 MPa, nearly 45 times higher than PVA−TA thread with no alignment. Wide-angle Xray two-dimensional diffraction images further confirmed the alignment of PVA fibers in stretching direction. In addition, we applied the PVA−TA hydrogel as suture and evaluated the cytotoxicity and biocompatibility of the PVA−TA suture.

Self-healing hydrogels have attracted intense attention because of their potential applications in ionic strain sensors.

In this work, we prepare guar gum-based supramolecular hydrogel through the formation of borate/didiol bonds. This dynamic and reversible noncovalent borate/didiol interaction is critical for the multifunctional properties of supramolecular hydrogel. The FT-IR and XRD analysis verified the existence of boronate ester interactions between borax and guar gum. Moreover, the viscoelastic and mechanical behaviors of the hydrogels with different guar gum concentrations showed that the storage modulus and compressive stress were highest at guar gum concentration of 2 wt %. Besides, due to the dynamic and reservable properties of boronate ester, these guar gum-based hydrogels had excellent self-healing property, outstanding reformable and injectable capability. In addition, hydrogels also exhibited reversible gel–sol transformations by the application of physicochemical stimuli such as thermal and pH value. The coupling of these multifunctional properties made from low-cost, environment friendly, and readily available materials could have potential applications in many biomedical areas in the future. We expect that this simple strategy of fabricating the self-healing guar gum hydrogels with multistimuli responsive properties may enrich the avenue in the exploration of multifunctional guar gum based hydrogels to expand their potential applications in various fields.

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