Direct Observation of Damage Zone around Crack Tips in Double-Network Gels

Yu, Qiu Ming; Takai, Yoshimi; Furukawa, Hidemitsu; Kurokawa, Takayuki; Gong, Jian Ping

doi:10.1021/ma900622s

Cited by 169 publications

(176 citation statements)

References 18 publications

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“…This indicates that the DN structure in the pores plays an important role in increasing the strength of the gel-substrate interface, which can be understood from the toughening mechanism observed for the DN gels [28][29][30][31][32][33]. When a conventional gel that consist of a single-network is broken, only the polymer chains located at the tip of a crack are ruptured; a very small amount of energy (1-10 J/m 2 for a conventional gel) is required for this rupturing [34] is needed.…”

Section: Resultsmentioning

confidence: 88%

Formation of a strong hydrogel–porous solid interface via the double-network principle

et al. 2010

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Section: Resultsmentioning

confidence: 88%

Formation of a strong hydrogel–porous solid interface via the double-network principle

et al. 2010

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“…As a result, the crack propagation in DN gels is retarded. 26,27 To relate the brittle-ductile transition to little energy dissipation up to a certain strain (we assign it as the 'threshold strain for energy dissipation', ε threshold ) and then the energy dissipation increases linearly with increasing strain, in consistence with our recent works. 18 On the other hand, the brittle DN (4/1) shows almost no energy dissipation and fractures immediately once it reaches the ε threshold .…”

Section: Mechanical Hysteresis Behaviormentioning

confidence: 75%

Brittle–ductile transition of double network hydrogels: Mechanical balance of two networks as the key factor

Ahmed

Nakajima

Kurokawa

et al. 2014

Polymer

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Tough double network (DN) hydrogels are a kind of interpenetrating network (IPN) gels with a contrasting structure; it consists of a rigid and brittle 1 st network with dilute, densely cross-linked short chains and a soft and ductile 2 nd network with concentrated, loosely cross-linked long chains. In this work, we focus on how the brittle gel changes into a tough one by increasing the amount of ductile component. By comparing the molecular structures of the individual first network and second network gels, we found that the true key factor that controls the brittleductile transition is the density of elastically effective polymer strands of the two networks, and . When / < 1, the second network fractures right after the fracture of the first network, and the gels are brittle. When / > 1, only the first network fractures. As a result, the brittle first network serves as sacrificial bonds, imparting toughness of DN gels. This result provides essential information to design tough materials based on the double network concept.3

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“…In particular, the Mullins effect has been considered as the major factor to explain the softening of double network hydrogels over consecutive loading cycles [48][49][50][51][52][53][54], and has been attributed to progressive damage of the polymer networks [50,55]. All these studies, however, have been focused on the initial several loading cycles.…”

Section: Shakedown After Prolonged Cyclingmentioning

confidence: 99%

Fatigue fracture of tough hydrogels

Bai

Yang

Tang

et al. 2017

Extreme Mechanics Letters

233

186

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Abstract:Tough hydrogels of many chemical compositions have been developed in recent years, but their fatigue fracture has not been studied. The lack of study hinders further development of hydrogels for applications that require long lifetimes under cyclic loads. Examples include tissue engineering, soft robots, and stretchable electronics. Here we study the fatigue fracture of a polyacrylamide-alginate tough hydrogel. We find that the stress-stretch curve changes cycle by cycle, and reaches a steady state after thousands of cycles. The threshold for fatigue fracture is about 53 J/m 2 , much below the fracture energy (~10,000 J/m 2 ) measured under monotonic load. Nonetheless, the extension of crack per cycle in the polyacrylamide-alginate tough hydrogel is much smaller than that in a single-network polyacrylamide hydrogel.

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Direct Observation of Damage Zone around Crack Tips in Double-Network Gels

Cited by 169 publications

References 18 publications

Formation of a strong hydrogel–porous solid interface via the double-network principle

Formation of a strong hydrogel–porous solid interface via the double-network principle

Brittle–ductile transition of double network hydrogels: Mechanical balance of two networks as the key factor

Fatigue fracture of tough hydrogels

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