Ultra-Low Hysteresis Under Large Deformation Enabled by Fast Chains Relaxation in Highly Competitive Dynamic Hydrogen Bond Networks.

High-quality capture of diverse motion signals in flexible sensors requires soft sensing materials to perform signal conversion and transmission stably and without delay over extended periods. However, low hysteresis achieved through purely elastic mechanisms easily exhibits poor crack propagation resistance. By leveraging the significant gap between the strain rate during large-strain service conditions and the crack propagation rate in the fracture process, this study presents a facile strategy for constructing a highly competitive dynamic hydrogen bonding system to produce near-zero-hysteresis and highly crack-resistant D-gels. Through tuning the relaxation dynamics of strong hydrogen bonding interactions with polymer segments by insert deep eutectic solvent (DES) components, the highly dynamic hydrogen bonds are rendered mechanically "invisible" during service condition-an essential factor in achieving a low-hysteresis attribute (low hysteresis: <3%). Meanwhile, the relaxation time of those dynamic bonds is comparable to the inverse of crack propagation rate, effectively alleviating stress concentration at the crack tips, thereby enhancing the ultimate fracture strain (1500%) and crack propagation strain (550%) of the gels. This approach provides a general strategy for synthesizing gels that overcome the traditional trade-off between high crack propagation resistance and high elasticity.