Fig. 2.

Mechanical properties of PVA/MF-CH. a Force-strain curve of the PVA hydrogel with different freeze-thaw cycles (4, 6, and 8). b Optical images of PU microfiber networks prepared with different electrospinning times (40 s, 2 min, 5 min, and 8 min). c Force-strain curves of PVA/MF-CH composed of PU microfiber networks with different electrospinning times (40 s, 2 min, 5 min, and 8 min) and PU microfiber networks with different electrospinning times of 2, 5, and 8 min. d Schematic thickness change of PVA/MF-CH with the increase of rotation rate. The thickness of the microfiber composite hydrogel (d) is comprised of the thickness of the microfiber network (d₁) and the thickness of the PVA hydrogel over the microfiber network (d₂) which can be controlled by the rotation rate during the spinning-coating procedure. e Thickness of PVA/MF-CHs processed under different rotation rates. f Force-strain curves of the PVA/MF-CH processed under different rotation rates of 0.5, 1.0, 2.0, and 3.0 k rpm. g Schematic anti-tearing behavior of microfiber composite hydrogel. h Digital images of PVA/MF-CH with a cut crack under different strains. i Maximum strains of PVA/MF-CHs and pure PVA hydrogels with and without a crack