Tough and recoverable triple‐network hydrogels based on multiple pairs of toughing mechanisms with excellent ionic conductivity as stable strain sensors

Abstract

The emerging applications of hydrogels in flexible devices require it possess multifunctional properties including stable mechanical and functions under various deformations or external environments. Herein, a multifunctional polyvinyl alcohol/M‐alginate/PAM hydrogel with very excellent mechanical properties and sensing functions was fabricated by introducing multiple pairs of toughing mechanisms into triple network (TN). The multiple supramolecular physical networks work as sacrificial networks to toughen the materials when hydrogel deforms. The broken bonds can reform upon unloading endowing the recovery of hydrogels' properties and functions with the assistance of the elastic covalent network. The optimal TN hydrogels are extremely tough (a fracture strength of 512 kPa, a fracture toughness of 3 MJ/m3) and recoverable from fatigue damage (~77% toughness recovery after 5 min resting at room temperature). The presence of abundant ionic species endows the tough and recoverable TN hydrogels high ionic conductivity and high sensitivity as strain sensors. Moreover, such TN hydrogels with multi‐bond crosslinking in three networks can potentially guarantee stable mechanical and sensor functions under various deformations or external environments compared to the DN candidates. This work provides a simple strategy for fabricating multifunctional hydrogels with high stability to fulfill its flexible devices applications. POLYM. ENG. SCI., 59:1657–1666 2019. © 2019 Society of Plastics Engineers

A Synthetic Hydrogel Composite with the Mechanical Behavior and Durability of Cartilage

“…A,B) Plots of the compressive versus tensile strength and modulus for BC–PVA–PAMPS (this work) and other strong hydrogels (see Table S1 in the Supporting Information for data and references). [ 13–35 ] The multiple data points for BC–PVA–PAMPS are for different compositions. C) BC–PVA–PAMPS easily bears the weight of a 100 lb.…”

A Dual Physical Cross‐Linking Strategy to Construct Tough Hydrogels with High Strength, Excellent Fatigue Resistance, and Stretching‐Induced Strengthening Effect

“…Among DC hydrogels, DPC hydrogels [38] attract much more attention due to their excellent stiffness, toughness, anti-fatigue, and selfrecoverability. Diverse physical interactions could be utilized to construct DPC hydrogels, such as hydrogen bonding, [39,40] hostguest interaction, [41,42] ionic coordination (IC), [43,44] HA, [45,46] crystallization, [47,48] chain entanglement, [49,50] and dipole-dipole interaction. [51,52] Inspired by the synergistic enhancement of rigid and flexible networks in DN hydrogels, the synergistic effect of strong and weak interactions is anticipated to endow DPC hydrogels with outstanding mechanical performances.…”

Biocompatible and Enzymatically Degradable Gels for 3D Cellular Encapsulation under Extreme Compressive Strain

“…This low strain level is in part due Gels 2021, 7,101 to the fact that common cytocompatible polymer hydrogels such as alginate and gelatin methacryloyl (GelMA), along with certain explanted soft tissues, typically fail at or below 50% compressive strain [22][23][24]. In contrast, existing hydrogels optimized for very high toughness and strain tolerance are frequently unsuitable for cell encapsulation due to toxic components or inhospitable gelation conditions [25][26][27]. This limitation presents a need for hydrogel scaffolds optimized for bulk compression of encapsulated cells at very high strain.…”