Journal ArticleDOI
Why are double network hydrogels so tough
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TLDR
In this article, double-network gels are characterized by a special network structure consisting of two types of polymer components with opposite physical natures: the minor component is abundantly crosslinked polyelectrolytes (rigid skeleton) and the major component comprises of poorly cross-linked neutral polymers (ductile substance).Abstract:
Double-network (DN) gels have drawn much attention as an innovative material having both high water content (ca. 90 wt%) and high mechanical strength and toughness. DN gels are characterized by a special network structure consisting of two types of polymer components with opposite physical natures: the minor component is abundantly cross-linked polyelectrolytes (rigid skeleton) and the major component comprises of poorly cross-linked neutral polymers (ductile substance). The former and the latter components are referred to as the first network and the second network, respectively, since the synthesis should be done in this order to realize high mechanical strength. For DN gels synthesized under suitable conditions (choice of polymers, feed compositions, atmosphere for reaction, etc.), they possess hardness (elastic modulus of 0.1–1.0 MPa), strength (failure tensile nominal stress 1–10 MPa, strain 1000–2000%; failure compressive nominal stress 20–60 MPa, strain 90–95%), and toughness (tearing fracture energy of 100∼1000 J m−2). These excellent mechanical performances are comparable to that of rubbers and soft load-bearing bio-tissues. The mechanical behaviors of DN gels are inconsistent with general mechanisms that enhance the toughness of soft polymeric materials. Thus, DN gels present an interesting and challenging problem in polymer mechanics. Extensive experimental and theoretical studies have shown that the toughening of DN gel is based on a local yielding mechanism, which has some common features with other brittle and ductile nano-composite materials, such as bones and dentins.read more
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Journal ArticleDOI
Physical hydrogels composed of polyampholytes demonstrate high toughness and viscoelasticity
Tao Lin Sun,Takayuki Kurokawa,Shinya Kuroda,Abu Bin Ihsan,Taigo Akasaki,Koshiro Sato,Md. Anamul Haque,Tasuku Nakajima,Jian Ping Gong +8 more
TL;DR: It is reported that polyampholytes, polymers bearing randomly dispersed cationic and anionic repeat groups, form tough and viscoelastic hydrogels with multiple mechanical properties.
Journal ArticleDOI
25th Anniversary Article: Engineering Hydrogels for Biofabrication
Jos Malda,Jos Malda,Jetze Visser,Ferry P.W. Melchels,Ferry P.W. Melchels,Tomasz Jungst,Wim E. Hennink,Wouter J.A. Dhert,Jürgen Groll,Dietmar W. Hutmacher,Dietmar W. Hutmacher +10 more
TL;DR: This review focuses on the deposition process, the parameters and demands of hydrogels in biofabrication, with special attention to robotic dispensing as an approach that generates constructs of clinically relevant dimensions.
Journal ArticleDOI
25th Anniversary Article: Rational Design and Applications of Hydrogels in Regenerative Medicine
Nasim Annabi,Nasim Annabi,Ali Tamayol,Ali Tamayol,Jorge Alfredo Uquillas,Jorge Alfredo Uquillas,Mohsen Akbari,Mohsen Akbari,Luiz E. Bertassoni,Luiz E. Bertassoni,Chaenyung Cha,Chaenyung Cha,Gulden Camci-Unal,Gulden Camci-Unal,Mehmet R. Dokmeci,Mehmet R. Dokmeci,Nicholas A. Peppas,Ali Khademhosseini,Ali Khademhosseini +18 more
TL;DR: The development of advanced hydrogel with tunable physiochemical properties is highlighted, with particular emphasis on elastomeric, light‐sensitive, composite, and shape‐memory hydrogels, and a number of potential applications and challenges in the utilization in regenerative medicine are reviewed.
Journal ArticleDOI
Multi-scale multi-mechanism design of tough hydrogels: building dissipation into stretchy networks
TL;DR: It is shown that tough hydrogels generally possess mechanisms to dissipate substantial mechanical energy but still maintain high elasticity under deformation, and a particularly promising strategy for the design is to implement multiple mechanisms across multiple length scales into nano-, micro-, meso-, and macro-structures of hydrogel.
Journal ArticleDOI
Self-Healing Hydrogels
TL;DR: The trends indicate that hydrogels that self-heal better also achieve self- healing faster, as compared to gels that only partially self- Healing, and the potential relevance of self-Healing hydrogel to the exciting research areas of 3D/4D printing, soft robotics, and assisted health technologies is highlighted.
References
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TL;DR: The composition and synthesis of hydrogels, the character of their absorbed water, and permeation of solutes within their swollen matrices are reviewed to identify the most important properties relevant to their biomedical applications.
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Double‐Network Hydrogels with Extremely High Mechanical Strength
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Nanocomposite Hydrogels: A Unique Organic–Inorganic Network Structure with Extraordinary Mechanical, Optical, and Swelling/De‐swelling Properties
TL;DR: In this paper, a novel nanocomposite hydrogels (NC gels) with a unique organic-inorganic (clay) network structure have been synthesized by in-situ free radical polymerization.
Journal ArticleDOI
Hydrogels in controlled release formulations: network design and mathematical modeling
Chien-Chi Lin,Andrew T. Metters +1 more
TL;DR: The objective of this article is to review the fundamentals and recent advances in hydrogel network design as well as mathematical modeling approaches related to controlled molecule release from hydrogels.