Fig. 3: Highly compressible and fatigue-resistant properties of CCAP hydrogel.
a, Compressive stress–strain curves under cyclic compression. The photographs show the hydrogel before and after 500 compression cycles. b, Stress–strain curves at up to 50% strain for up to 3 × 104 cycles and at 15% strain for up to 105 cycles. c, Time-dependent swelling ratio of the CCAP hydrogel in terms of height and diameter. d, Photographs showing CCAP, DF-PAM and Ag/PAM hydrogels enduring a weight of 5 g after swelling in water for 10 days. e, Loading–unloading stress–strain curves at different compressive strains in water. f, Stress–strain curves at up to 50% strain for up to 5 × 104 cycles and at 15% strain for up to 5 × 105 cycles in water. g, Energy loss coefficient, maximum stress and residual strain over 5 × 104 cycles at 50% strain in water. h, Ashby chart showing residual strain versus compressive strain during long-term compression cycles of CCAP hydrogel compared with previously reported materials. The cycle numbers are marked next to the symbols with references in parentheses. The red, green, blue, pink and yellow hollow diamonds represent elastic materials using graphene14,15,17, carbon nanotubes8,23,25, carbon nanofibres19,20, two carbon materials29,30,31 and organic-derived species9,26 as building blocks, respectively. The purple solid diamond represents compression in water35. The red and green spheres in the blue area represent our CCAP hydrogel compressed in air and water, respectively. i, Schematic showing CCAP hydrogel with an interconnected lamellar network and a porous cell wall resistant to compression force (F). j, Schematic illustration of the energy-dissipation mechanism from three recoverable elements: (1) reversible elastic bending of the AgNW network at the nanoscale (F′1), (2) reversible radial buffer of porous structure at the microscale (F′2) and (3) global relaxation in the interconnected AgNW/PAM network at the macroscale (F′3).
