Hybrid Hydrogels with Extremely High Stiffness and Toughness

Li, Jianyu; Illeperuma, Widusha Ruwangi Kaushalya; Suo, Zhigang; Vlassak, Joost J.

doi:10.1021/mz5002355

Cited by 388 publications

(324 citation statements)

References 44 publications

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“…The stretchable materials in the current work are compared with other materials, e.g., natural rubbers [47,66], polyacrylamide hydrogels [26], alginate hydrogels [26,67], and tough hydrogels, [26,68], as well as steels, aluminum, bone, human skin, acrylic glass, epoxy, aluminum oxide, and silica glass. [69] For brittle hard solids (e.g., a silica glass), measuring σ * and W * in the small-flaw limit is a difficult experimental task, and is rarely done in practice, because the small-flaw limit is reached when the flaws approach the atomic scale. In practice, brittle hard solids nearly always operate in the large-flaw limit, where the Griffith fracture mechanics applies.…”

Section: Flaw Sensitivity Of Various Materialsmentioning

confidence: 99%

Flaw sensitivity of highly stretchable materials

Chen

Wang

Suo

2017

Extreme Mechanics Letters

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196

135

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Elastomers and gels can often deform multiple times their original length. The stretchability is insensitive to small cuts in the samples, but reduces markedly when the cuts are large. We show that this transition occurs when the depth of cut exceeds a material-specific length, defined by the ratio of the fracture energy measured in the large-cut limit and the work to rupture measured in the small-cut limit. This conclusion generalizes a result in the fracture mechanics of hard materials. For an acrylic elastomer and a polyurethane, we measure the stretch to rupture as a function of the depth of cut, and show that the experimental data agree well with the prediction of the nonlinear elastic fracture mechanics. In a space of material properties we compare many materials (elastomers, gels, ceramics, glassy polymers, biomaterials, and metals), and find that the material-specific length varies from nanometers to centimeters.

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Section: Flaw Sensitivity Of Various Materialsmentioning

confidence: 99%

Flaw sensitivity of highly stretchable materials

Chen

Wang

Suo

2017

Extreme Mechanics Letters

Self Cite

196

135

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“…Lately, new classes of materials are becoming available that join natural rubber as elastic, yet brittle, materials that can sustain large background strains prior to fracture. The fracture resistance of some of these synthetic materials, such as double-network hydrogels made of ionically and covalently cross-linked networks [214][215][216][217][218][219], can be made to be enormous and new applications are expected to abound [220,221]. In addition to such "chemical gels", there is also clear experimental evidence that elastic nonlinearities are important to fracture processes in "physical gels" [108], i.e.…”

Section: Future Directionsmentioning

confidence: 99%

Recent developments in dynamic fracture: some perspectives

Fineberg

Bouchbinder

2015

Int J Fract

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We briefly review a number of important recent experimental and theoretical developments in the field of dynamic fracture. Topics include experimental validation of the equations of motion for straight tensile cracks (in both infinite media and strip geometries), validation of a new theoretical description of the near-tip fields of dynamic cracks incorporating weak elastic nonlinearities, a new understanding of dynamic instabilities of tensile cracks in both 2D and 3D, crack front dynamics, and the relation between frictional motion and dynamic shear cracks. Related future research directions are briefly discussed.

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“…When a hybrid gel is subject to external force the crosslinks are "unzipped", dissipating dissociation energy of the ionic bonds and entropic energy of the loaded network strands. High toughness of the hybrid gel is obtained when the alginate network is highly-crosslinked and the PAAm network is loosely-crosslinked [9,[14][15][16][17][18], which mirrors the topologies known to maximize toughness in DN gels [19]. The ionic bonds that are pulled apart during the hybrid gel deformation are re-formed at zero-stress at a temperature-induced network recovery process to largely retrieve the mechanical properties of the virgin gel [9].…”

mentioning

confidence: 91%

Time-dependent mechanical properties of tough ionic-covalent hybrid hydrogels

Xin

Brown

Naficy

et al. 2015

Polymer

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Hybrid gels featuring interpenetrating covalent and ionic crosslinked networks have recently been shown to exhibit both high toughness and recoverability of strain-induced network damage. The high toughness results from the energy dissipated as entropically strained network strands are released by the dissociation of ionic crosslinks. As in the so-called double network hydrogels, the toughening process is inherently linked to network damage. This damage, however, can be recovered to a large degree in hybrid gels due to the reformation of ionic associations when the gel is unloaded. The stability of the ionic network under load is here investigated and it is shown that these networks show large stress relaxation at constant strain, time dependent stress-strain behaviour and rate-dependent toughness. A double exponential model is invoked to mathematically describe the stress relaxation of the hybrid gels indicating at least two relaxation mechanisms. The rate-dependent toughness and the relaxation behaviour of the hybrid gels are attributed to the labile unzipping of the ionic crosslinks which is assumed to be load and time dependent. AbstractHybrid gels featuring interpenetrating covalent and ionic crosslinked networks have recently been shown to exhibit both high toughness and recoverability of strain-induced network damage. The high toughness results from the energy dissipated as entropically strained network strands are released by the dissociation of ionic crosslinks. As in the socalled double network hydrogels, the toughening process is inherently linked to network damage. This damage, however, can be recovered to a large degree in hybrid gels due to the reformation of ionic associations when the gel is unloaded. The stability of the ionic network under load is here investigated and it is shown that these networks show large stress relaxation at constant strain, time dependent stress-strain behaviour and rate-dependent toughness. A double exponential model is invoked to mathematically describe the stress relaxation of the hybrid gels indicating at least two relaxation mechanisms. The ratedependent toughness and the relaxation behaviour of the hybrid gels are attributed to the labile unzipping of the ionic crosslinks which is assumed to be load and time dependent.

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Hybrid Hydrogels with Extremely High Stiffness and Toughness

Cited by 388 publications

References 44 publications

Flaw sensitivity of highly stretchable materials

Flaw sensitivity of highly stretchable materials

Recent developments in dynamic fracture: some perspectives

Time-dependent mechanical properties of tough ionic-covalent hybrid hydrogels

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