Fig. 2

Modelling of the mechanical properties and toughness of the hydrogels. a Tensile stress-strain curves of hydrogel fibres with optimised mechanical properties under different humidity values. The twist density was 7 turns mm⁻¹, and the deformation rate was 27.8% s⁻¹. b The Young’s modulus, toughness, and gravimetric toughness of the hydrogel fibres as a function of the twist density. The deformation rate was 27.8% s⁻¹. c FEM simulation results of the engineering stress-strain curves of the hydrogel fibres (dotted line) with the same diameter (50 μm) but different drying times; the solid curves represent the experimental data. d Comparison of the energy dissipation and damping capacity of hydrogel fibres (pink stars) in this work with those of other typical energy-dissipation materials, such as hydrogel (green symbols), spider silk (yellow symbols), protein-based fibres (blue symbols) and synthetic fibres (red symbols), reported in the literature. The numbers shown in the graphs correspond to the references. The hydrogel fibres presented different twist densities and were tested at different deformation rates. All the hydrogel fibres contained 0.1 wt% VSNPs and 20 mM ZnCl₂. e, f The ¹H double-quantum/single-quantum (DQ/SQ) chemical shift correlation spectra at 40 kHz MAS of samples: e without and f with ZnCl₂. Two rotor periods of Back-to-Back (BABA) recoupling were used for the excitation and reconversion of the DQ coherence. The error bars mean the s.d. from five measurements