Fig. 3: Mechanical properties and self-healing capability of DSE.

a Typical stress-strain curves of DSE-0~3. Maximum strain and stress reach 1630.53% and 42.60 MPa for DSE-3 with a 30% UPy motif, respectively. b Toughness of DSE-0~3. It is calculated by the integrate area of the stress-strain curves. Error bars represent the standard deviation calculated by the data sets (n = 3). c Successive cyclic tensile behavior of DSE-3 at different strains (100%, 300%, 500%, 700%). The larger the tensile strain, the more pronounced the hysteresis loop, which indicated that DSE can effectively dissipated strain energy (a key feature for high toughness) caused by the breaking of dynamic bonds during stretching–retraction cycles at the different strains. d Digital images for DSE-3 film that can restore to its original length after being stretched to 300% strain. e Consecutive cyclic tensile curves of DSE-3 at a strain of 300%. After relaxing for 10 min, the cycle curve was fully overlapped with the first cycle, indicating the full self-recoverability of DSE. f Photograghs of the intact DSE-3 sample and one with the precut crack stretched to 4 times its original stretching. g Stress-strain curves of the intact DSE-3 sample and one with the precut crack (gauge length: 10 mm). The fracture energy (Γ) is calculated by the formula: Γ = Hw(λc). h Optical microscopy images of the scratched and healed DSE-2 film. Healed condition: 12 h at ambient environment. i Stress–strain curves of the original and self-healed DSE-2 specimens after different healing time from 2 h to 48 h at r. t. and 60 °C for 2 h. All stretching rate: 100 mm min⁻¹.