Unbreakable Hydrogels with Self‐Recoverable 10 200% Stretchability

Abstract

Design of tough hydrogels maintaining structural integrity under multivariable mechanical loads remains hugely challenging because the anticipated characteristics such as stretchability, strength, toughness, and fracture resistance can hardly be compatible. Herein, a simple but robust hydrogel network formed by copolymerization of divinyl benzene with acrylamide in micellar solutions for ultra‐high fracture resistance and self‐recoverable stretchability is proposed. The network provides dynamic association of hydrophobic domains and homogeneous crosslinking of hydrophilic chains, which shows step‐by‐step deformation process. The dynamic associations allow recoverable small deformations, then the homogeneous crosslinking ensures reversible unfolding and alignment of polymer chains to self‐strengthen for ultra‐large deformations without crack propagations. The resultant hydrogels exhibit comprehensive unbreakable feature with self‐recoverable ultra‐high stretchability (100% recovery from 10 200% strain), superior fracture resistance (toughness > 26 kJ m−2), and anticrack propagation and fatigue (fatigue threshold: ≈2.5 kJ m−2). Even the prenotched hydrogels can undergo tens cyclic loads at 10 200% strain and thousands cyclic loads at 200% strain without noticeable changes in mechanical performance. The robust network prepared from homogeneous hydrophobic crosslinking provides a facile approach and a new mechanism to explore tough hydrogels with superior antifracture and extreme self‐recoverable deformability for diverse applications.

Robust hydrogel sensors for unsupervised learning enabled sign‐to‐verbal translation

“…Within a certain stretching range, the crosslinked network not only remains unbroken but also keeps a reversible stretching property. These properties give the mechanical robustness to the LM‐H 52 …”

“…Within a certain stretching range, the crosslinked network not only remains unbroken but also keeps a reversible stretching property. These properties give the mechanical robustness to the LM-H. 52 The hysteresis under deformations is an important consideration for wearable electronics as their application scenarios inevitably encounter various mechanical deformations which may cause device failure. 53 Figure 2F shows the loading-unloading curves of LM-H with 1.4 wt.% EGaIn content at room temperature at a tensile strain of 400% in which LM-H strain sensors exhibit low hysteresis of 7.5%.…”

Carbon Quantum Dot/Chitosan‐Derived Hydrogels with Photo‐stress‐pH Multiresponsiveness for Wearable Sensors

“…Because hydrogels are extremely vulnerable, [41,42] more and more researchers have focused on preparing hydrogels with excellent mechanical properties [43][44][45][46][47][48] for better applications in wearable flexible sensors, electronic skins, [49] and batteries, [50,51] etc. Among them, the preparation of double network hydrogels [52,53] by physical or chemical cross-linking is efficient to obtain highly stretchable and tough properties.…”

Dual-Stimuli-Responsive and Anti-Freezing Conductive Ionic Hydrogels for Smart Wearable Devices and Optical Display Devices

“…Artificially intelligent materials have attracted considerable attention in recent years for their ability to convert monitored macroscopic and subtle changes caused by external forces (and deformations) into electrical signals, − a property that makes them useful in areas such as bionic skins, , wearable electronic devices, and human–computer interaction . Among the various types of conventional conductive materials, ion-conductive hydrogels have emerged as the most promising flexible materials because of their high similarity to natural soft tissues, good mechanical adaptability to organs such as skin and muscles, − good ionic conductivity, , and excellent stretchability. − Currently, research on ion-conductive hydrogels lies in improving their transparency, , electrical sensing sensitivity, anti-freezing properties, − and mechanical properties. − …”