Fig. 4. (a) Photos showing the stretching of GA/SA DN hydrogel, (b) tensile curves of the GA/SA DN hydrogels, (c) tensile strain of the GA/SA DN hydrogels and SA hydrogels as a function of SA content, (d) elastic modulus of the GA/SA DN hydrogels, (e) compressive curves of the GA/SA DN hydrogels and SA₃ hydrogel, (f) the corresponding compression stress and strain values, and (g) photos showing the compression behaviors of GA/SA₃ DN hydrogel (top) and SA₃ hydrogel (bottom).