Stimuli-Responsive Toughening of Hydrogels

Abstract

Materials with stimuli-switchable properties are widespread in nature. Through biomimicry, stimuli-responsive hydrogels have received increasing research in recent years. In particular, hydrogels with stimuli-tunable mechanical properties provide an important platform for designing new materials with specific applications such as 3D printing, soft robot, and tunable adhesion. Herein, the state-of-the-art of hydrogels with stimuli-responsive toughness is reviewed in detail. Characteristic reinforcement mechanisms are fully discussed first, followed by systematical demonstrations of various smart hydrogels responding to various stimuli. In particular, special attention is paid to thermal, light, pH, and salt triggers because of their broad applications and easy implementation. Furthermore, the applications of these smart hydrogels are included. In addition to the overview of recent advances, we finally summarize the critical challenges of current discoveries and make an outlook for the following work, which we anticipate to lead to substantial progress of these responsive materials in the future.

Multifunctional Arabinoxylan-functionalized-Graphene Oxide Based Composite Hydrogel for Skin Tissue Engineering

“…After absorbing wound exudate, the composite hydrogel swells during application. An ideal hydrogel material with optimized cross-linking will preserve structural integrity without dissolving or breaking, allowing it to absorb the maximum amount of biofluid and thereby guard against bacterial attack ( Lin et al, 2021 ). The mechanical strength of composite hydrogels can be optimized by cross-linker amount.…”

Dually‐Thermoresponsive Hydrogel with Shape Adaptability and Synergetic Bacterial Elimination in the Full Course of Wound Healing

“…[ 19 ] Due to physical interactions generated in the phase separation like hydrophobic or hydrogen bonding interactions, the mechanical properties of the hydrogels can be tuned by temperature and thus achieve a phase‐separation‐induced reinforcement at both high and low temperatures. [ 20,21 ] Inspired by this, a dually‐thermoresponsive hydrogel with lower mechanical strength to achieve compliance in the temperature range of UCST<T<LCST may be designed to realize shape‐adaptability to fill irregular wounds.…”

Advances in ultrasound-responsive hydrogels for biomedical applications

“…Inspired by the reversible elongation and contraction of muscles under stimulation conditions, the rapid closure of leaves of mimosa when touched, and the ability of chameleons to change color according to different environments and other behaviors in response to external conditions, intelligent responsive hydrogels have gradually been developed and attracted more and more attention. 35,36 Intelligent hydrogels are a class of hydrogels with the ability to undergo swelling-shrinkage or gel-sol transition under the stimulation of the surrounding environment. Compared with traditional hydrogels, intelligent hydrogels can achieve multiple, variable, controllable and reversible changes in their shape and properties in a manner of space or time, thus greatly adapting to the complex application environment in vitro and in vivo.…”

“…Inspired by the reversible elongation and contraction of muscles under stimulation conditions, the rapid closure of leaves of mimosa when touched, and the ability of chameleons to change color according to different environments and other behaviors in response to external conditions, intelligent responsive hydrogels have gradually been developed and attracted more and more attention. 35,36…”