On the Race for More Stretchable and Tough Hydrogels

Abstract

Hydrogels are tridimensional networks that are able to retain important amounts of water. These soft materials can be obtained through self-assembling processes involving either hydrophilic molecules or polymers, allowing the formation of the corresponding covalently and physically cross-linked networks. Although the applicability of hydrogels in biomedicine has been exponentially growing due to their biocompatibility and different responses to stimuli, these materials have exhibited the particular feature of poor mechanical strength, and consequently, are brittle materials with low deformation. Due to this reason, a race has started to obtain more stretchable and tough hydrogels through different approaches. Within this context, this review article describes the most representative strategies and examples involving synthetic polymers with potential for biomedical applications.

Ionic Tactile Sensors for Emerging Human‐Interactive Technologies: A Review of Recent Progress

“…However, they also undergo some kinds of challenges. For example, conventional crosslinked polyacrylamide hydrogels have low mechanical properties, limited stretchability, which leads to unfavorable feature to 3D curved and dynamic surfaces . Novel strategies including double‐networks, nanocomposites, dynamic cross‐linking have been developed to synthesize novel hydrogels with improved mechanical properties and even with self‐healing capabilities.…”

Specialty Tough Hydrogels and Their Biomedical Applications

“…[78] One important consideration when using such materials for medical purposes is the in vivo degradation and subsequent the fate of the nanoparticles released from the composite materials. [13] Moreover, choosing the appropriate nanoparticles becomes critical, as different nanoparticles demonstrate different levels of biocompatibility, and the mechanical and self-recovery properties of the composite gels have been found to be affected by the choice of nanoparticle. [13]…”

“…[13] Moreover, choosing the appropriate nanoparticles becomes critical, as different nanoparticles demonstrate different levels of biocompatibility, and the mechanical and self-recovery properties of the composite gels have been found to be affected by the choice of nanoparticle. [13]…”

“…These limitations have drawn attention to designing materials with enhanced stretchable and toughness properties. [5][6][7][8][9][10][11][12][13][14] However, formulating mechanically robust hydrogels that are also morphologically and chemically stable for clinical use remains a challenge. For example, disruption of covalent bonds in tough interpenetrating network hydrogels can lead to irreparable network damage, employing hydrophobic associations is hampered by poor solubility of hydrophobes, competition from water for binding sites limits the association strength of hydrogen bonds, and ionic crosslinks are vulnerable to mobile ions typically encountered in physiological conditions.…”

Dual Physically Cross‐Linked Hydrogels Incorporating Hydrophobic Interactions with Promising Repairability and Ultrahigh Elongation

“…Generally, a hydrogel with tensile stress oscillating between 0.1 and 1 MPa is commonly considered to be strong for satisfying its general applications. [ 14 ] However, for biological applications, the hydrogel is required to be not only strong to bear external stress but also promisingly stretchable to be used with human bodies, including skin and muscle, in a long time. [ 15 ] Therefore, how to design a robust and strong hydrogel with excellent elongation has received a wide range of interest.…”