Fig. 2

Compressive stress-strain curve (A-I) and compressive strength histogram of hydrogel (A-II); 8 cycles compressive stress-strain curve of Hep₂₀-PDA_0.8-rGO-PAM hydrogel at 50% of maximum strain (B); Tensile stress-strain curve (C-I), tensile stress histogram (C-II) and tensile strain histograms of the hydrogels (C-III) (a–g are as follows: (a) PAM (b) GO-PAM (c) Hep₂₀-rGO-PAM (d) PDA_0.8-rGO-PAM (e) Hep₂₀-PDA_0.2-rGO-PAM (f) Hep₂₀-PDA_0.4-rGO-PAM (g) Hep₂₀-PDA_0.8-rGO-PAM)