Ultra-stretchable and notch-insensitive hydrogels via the synergistic effect of multiple hydrogen bonding and electrostatic interaction for human motion detection

Conventional chemical crosslinking hydrogels have demonstrated their excellent mechanical properties, but they often exhibit negligible fatigue resistance and poor self-healing properties due to the irreversible damage in covalent-linked networks. Herein, a fully physical crosslinking hydrogel was prepared from 3-acrylamidopropyl trimethylammonium chloride (ATAC) and N,N-Dimethylaminopropyl acrylamide (DMAPAA) by one-pot freeradical copolymerization. Owing to electrostatic interactions assisted by multiple hydrogen bonds, the hydrogel exhibited outstanding mechanical behavior: tensile strain of 5793.8%, tensile strength of 257.6 kPa, Young' s modulus of 146.1 kPa, and fracture energy of 34.5 kJ/m2. Specially, the multiple hydrogen bonds and electrostatic effect in the hydrogel can evenly disperse stress of the polymer segments, thus passivating the initial crack and avoiding stress concentration. Considering the reversibility of multiple physical cross-linking networks, the hydrogel also displayed excellent self-healing properties. This work provides a simple route to fabricate highly tough, super-stretchable and notch-insensitive hydrogels, demonstrating their vast potential in the flexible electronic devices.