Extended Data Fig. 5: Compression properties of N-DC (FL)₈ hydrogels.

(a) Stress-strain curves of a N-DC (FL)₈ hydrogel compressed to failure. Inset shows the photographs of the hydrogel right after failure (1^st cycle) and after three more consecutive compression-unloading cycles (4^th cycle). Cracks were observed right after failure. Subsequent compression led to propagation of the crack, but the failure is not brittle. (b) Photographs of the N-DC (FL)₈ hydrogel during various stages of compression. After unloading, the hydrogel recovered its shape rapidly. (c) Schematics of the hydrogel network structure during compression-unloading. The structure is drawn in a highly schematic manner, and for illustration purpose only. Red circle indicates the chain entanglement, red arrows point to two folded FL domains that may undergo forced-unfolding at high strain, and then refolding after unloading. When compressed to 50% strain and then unloaded, the hydrogel can quickly recover. When compressed to 80% strain, a small number of FL domains unfold. Upon unloading, a large fraction of unfolded FL domains refolds quickly, while a small fraction refolds following a slower kinetics. For simplicity, hydrophobically collapsed FL aggregates are not shown. The force-induced unfolding of the folded FL domains help dissipate energy during loading, and upon unloading, the refolding of FL domains help the hydrogel to regain its shape and mechanical properties. (d—e) Consecutive compression-unloading curves of a N-DC (FL)₈ hydrogel at a frequency of 0.08 Hz (d) and 0.67 Hz (e). The loading rate was 20 mm/min in (d) and 200 mm/min in (e). The N-DC hydrogels showed limited fatigue (insets). The percentage is the peak stress of each cycle compared to the initial stress when loaded to strain of 60%.