Tough hydrogels with rapid self-reinforcement

Abstract

Most tough hydrogels are reinforced by introducing sacrificial structures that can dissipate input energy. However, because the sacrificial damage cannot rapidly recover, the toughness of these gels drops substantially during consecutive cyclic loadings. We propose a damageless reinforcement strategy for hydrogels using strain-induced crystallization. For slide-ring gels in which polyethylene glycol chains are highly oriented and mutually exposed under large deformation, crystallinity forms and melts with elongation and retraction, resulting both in almost 100% rapid recovery of extension energy and excellent toughness of 6.6 to 22 megajoules per square meter, which is one order of magnitude larger than the toughness of covalently cross-linked homogeneous gels of polyethylene glycol.

Drug Delivery Based on Stimuli-Responsive Injectable Hydrogels for Breast Cancer Therapy: A Review

“…The hydrogels are composed of linear PEG chains crosslinked by ring-shaped hydroxypropyl-α-cyclodextrin (α-CDs) which are able to slide along the polymeric chains. In cyclic extension-relax tests, recoverable energy dissipation was observed owing to the orientation and dis-orientation of the PEG chains mediated by those moveable ring crosslinkers [ 107 ]. In another work, injectable double network hydrogels were prepared utilizing the guest-host association.…”

Untangling the mechanics of entanglements in slide-ring gels towards both super-deformability and toughness

“…Slide-ring (SR) gels exhibit good mechanical performance which is quite different from that of the conventional gels. 17–21 They have been constructed based on a strategy via threading the molecular chains into cross-linked rings, which are able to dynamically slip along the chain axis, thus retaining the same binding energy. 17–21 SR gels present a low mechanical strength because the sliding could proceed without much energy consumption.…”

Photothermal Detection of MicroRNA Using a Horseradish Peroxidase-Encapsulated DNA Hydrogel With a Portable Thermometer

“…Hydrophilic polymers can be dissolved in water without a defined shape, however, after cross-links, the solid-like three-dimensional structures are formed, which bring a uid-like properties ( Guan et al, 2020 ; Wei et al, 2020 ). Stimulus-responsive (or target-responsive) DNA hydrogels composed of multifunctional polymers as the backbone and functional DNA as the cross-linker are potential colorimetric sensors carrying enzymes because of their biocompatibility, encapsulation and release capability, flexibility, and mechanical stability ( Xiang and Lu, 2012 ; Kahn et al, 2017 ; Amalfitano et al, 2021 ; Liu et al, 2021 ). They are widely used for the determination of various targets including ions, small molecules, nucleic acids, and proteins ( Zhu et al, 2010 ; Lin et al, 2011 ; Yan et al, 2013 ).…”