Abstract
Although conventional polymer gels are known as mechanically weak materials, their fracture toughness can be effectively improved by introducing weak and brittle bonds into soft and stretchy polymer networks. This toughening method, denoted as the ‘sacrificial bond principle’, has been recently proposed by our group. When force is applied to such modified gels with an initial crack, brittle bonds surrounding the crack tip are widely and catastrophically ruptured prior to macroscopic crack propagation. As this extensive brittle bond fracture requires significant energy input, the total energy required for gel fracture is remarkably increased. Since the gel toughness is increased due to sacrificing the introduced brittle bonds, they are termed sacrificial bonds. In this focus review, I describe some extremely tough gels prepared by our group using this principle, e.g., double- or multiple-network gels with high water content featuring covalent sacrificial bonds, self-healing polyampholyte gels containing ionic sacrificial bonds, and PDGI/PAAm gels based on hydrophobic sacrificial bonds exhibiting stress-responsive structural colors.
Similar content being viewed by others
Log in or create a free account to read this content
Gain free access to this article, as well as selected content from this journal and more on nature.com
or
References
Osada, Y. & Kajiwara, K. Gels Handbook (eds Osada, Y., Kajiwara, K., Fushimi, T., Irasa, O., Hirokawa, Y., Matsunaga, T., Shimomura, T., Wang, L. & Ishida, H. ) (Elsevier, Inc., Amsterdam, Netherlands, 2001).
Li, Y. & Tanaka, T. Phase transitions of gels. Annu. Rev. Mater. Sci. 22, 243–277 (1992).
Gong, J. P. Friction and lubrication of hydrogels—its richness and complexity. Soft Matter 2, 544 (2006).
Kwon, H. J., Yasuda, K., Gong, J. P. & Ohmiya, Y. Polyelectrolyte hydrogels for replacement and regeneration of biological tissues. Macromol. Res. 22, 227–235 (2014).
Li, J. & Mooney, D. J. Designing hydrogels for controlled drug delivery. Nat. Rev. Mater. 1, 16071 (2016).
Caló, E. & Khutoryanskiy, V. V. Biomedical applications of hydrogels: a review of patents and commercial products. Eur. Polym. J. 65, 252–267 (2015).
Lake, G. J. & Thomas, A. G. The strength of highly elastic materials. Proc. R. Soc. A Math. Phys. Eng. Sci. 300, 108–119 (1967).
Akagi, Y., Sakurai, H., Gong, J. P., Chung, U. I. & Sakai, T. Fracture energy of polymer gels with controlled network structures. J. Chem. Phys. 139, 13251–13258 (2013).
Morton, M. Rubber Technology, 3rd edn (Springer, Berlin, Germany, 1987).
Zhao, X. Multi-scale multi-mechanism design of tough hydrogels: building dissipation into stretchy networks. Soft Matter 10, 672–687 (2014).
Kobayashi, T. Strength and Toughness of Materials, (Springer-Japan, Tokyo, Japan, 2004).
Gong, J. P. Why are double network hydrogels so tough? Soft Matter 6, 2583–2590 (2010).
Tanaka, Y., Fukao, K. & Miyamoto, Y. Fracture energy of gels. Eur. Phys. J. E 401, 395–401 (2000).
Gong, J. P., Katsuyama, Y., Kurokawa, T. & Osada, Y. Double-network hydrogels with extremely high mechanical strength. Adv. Mater. 15, 1155–1158 (2003).
Tanaka, Y., Kuwabara, R., Na, Y. H., Kurokawa, T., Gong, J. P. & Osada, Y. Determination of fracture energy of high strength double network hydrogels. J. Phys. Chem. B 109, 11559–11562 (2005).
Nakajima, T., Furukawa, H., Tanaka, Y., Kurokawa, T., Osada, Y. & Gong, J. P. True chemical structure of double network hydrogels. Macromolecules 42, 2184–2189 (2009).
Nakajima, T., Takedomi, N., Kurokawa, T., Furukawa, H. & Gong, J. P. A facile method for synthesizing free-shaped and tough double network hydrogels using physically crosslinked poly(vinyl alcohol) as an internal mold. Polym. Chem. 1, 693 (2010).
Huang, M., Furukawa, H., Tanaka, Y., Nakajima, T., Osada, Y. & Gong, J. P. Importance of entanglement between first and second components in high-strength double network gels. Macromolecules 40, 6658–6664 (2007).
Ahmed, S., Nakajima, T., Kurokawa, T., Anamul Haque, M. & Gong, J. P. Brittle-ductile transition of double network hydrogels: mechanical balance of two networks as the key factor. Polymer 55, 914–923 (2014).
Weng, L., Gouldstone, A., Wu, Y. & Chen, W. Mechanically strong double network photocrosslinked hydrogels from N,N-dimethylacrylamide and glycidyl methacrylated hyaluronan. Biomaterials 29, 2153–2163 (2008).
Suekama, T. C., Hu, J., Kurokawa, T., Gong, J. P. & Gehrke, S. H. Double-network strategy improves fracture properties of chondroitin sulfate networks. ACS Macro Lett 2, 137–140 (2013).
Na, Y. H., Tanaka, Y., Kawauchi, Y., Furukawa, H., Sumiyoshi, T., Gong, J. P. & Osada, Y. Necking phenomenon of double-network gels. Macromolecules 39, 4641–4645 (2006).
Webber, R. E., Creton, C., Brown, H. R. & Gong, J. P. Large strain hysteresis and mullins effect of tough double-network hydrogels. Macromolecules 40, 2919–2927 (2007).
Nakajima, T., Kurokawa, T., Ahmed, S., Wu, W. & Gong, J. P. Characterization of internal fracture process of double network hydrogels under uniaxial elongation. Soft Matter 9, 1955–1966 (2013).
Kawauchi, Y., Tanaka, Y., Furukawa, H., Kurokawa, T., Nakajima, T., Osada, Y. & Gong, J. P. Brittle, ductile, paste-like behaviors and distinct necking of double network gels with enhanced heterogeneity. J. Phys. Conf. Ser. 184, 12016 (2009).
Matsuda, T., Nakajima, T., Fukuda, Y., Hong, W., Sakai, T., Kurokawa, T., Chung, U.-I. & Gong, J. P. Yielding criteria of double network hydrogels. Macromolecules 49, 1865–1872 (2016).
Brown, H. R. A model of the fracture of double network gels. Macromolecules 40, 3815–3818 (2007).
Tanaka, Y. A local damage model for anomalous high toughness of double-network gels. Europhys. Lett. 78, 56005 (2007).
Tanaka, Y., Kawauchi, Y., Kurokawa, T., Furukawa, H., Okajima, T. & Gong, J. P. Localized yielding around crack tips of double-network gels. Macromol. Rapid Commun. 29, 1514–1520 (2008).
Yu, Q. M., Tanaka, Y., Furukawa, H., Kurokawa, T. & Gong, J. P. Direct observation of damage zone around crack tips in double-network gels. Macromolecules 42, 3852–3855 (2009).
Liang, S., Wu, Z. L., Hu, J., Kurokawa, T., Yu, Q. M. & Gong, J. P. Direct observation on the surface fracture of ultrathin film double-network hydrogels. Macromolecules 44, 3016–3020 (2011).
Saito, J., Furukawa, H., Kurokawa, T., Kuwabara, R., Kuroda, S., Hu, J., Tanaka, Y., Gong, J. P., Kitamura, N. & Yasuda, K. Robust bonding and one-step facile synthesis of tough hydrogels with desirable shape by virtue of the double network structure. Polym. Chem 2, 575 (2011).
Hu, J., Hiwatashi, K., Kurokawa, T., Liang, S. M., Wu, Z. L. & Gong, J. P. Microgel-reinforced hydrogel films with high mechanical strength and their visible mesoscale fracture structure. Macromolecules 44, 7775–7781 (2011).
Hu, J., Kurokawa, T., Hiwatashi, K., Nakajima, T., Wu, Z. L., Liang, S. M. & Gong, J. P. Structure optimization and mechanical model for microgel-reinforced hydrogels with high strength and toughness. Macromolecules 45, 5218–5228 (2012).
Hu, J., Kurokawa, T., Nakajima, T., Wu, Z. L., Liang, S. M. & Gong, J. P. Fracture process of microgel-reinforced hydrogels under uniaxial tension. Macromolecules 47, 3587–3594 (2014).
Nakajima, T., Sato, H., Zhao, Y., Kawahara, S., Kurokawa, T., Sugahara, K. & Gong, J. P. A universal molecular stent method to toughen any hydrogels based on double network concept. Adv. Funct. Mater. 22, 4426–4432 (2012).
Nakajima, T., Fukuda, Y., Kurokawa, T., Sakai, T., Chung, U. & Gong, J. P. Synthesis and fracture process analysis of double network hydrogels with a well-defined first network. ACS Macro Lett 2, 518–521 (2013).
Zhao, Y., Nakajima, T., Yang, J. J., Kurokawa, T., Liu, J., Lu, J., Mizumoto, S., Sugahara, K., Kitamura, N., Yasuda, K., Daniels, A. U. D. & Gong, J. P. Proteoglycans and glycosaminoglycans improve toughness of biocompatible double network hydrogels. Adv. Mater. 26, 436–442 (2014).
Ducrot, E., Chen, Y., Bulters, M., Sijbesma, R. P. & Creton, C. Toughening elastomers with sacrificial bonds and watching them break. Science 344, 186–189 (2014).
Argun, A., Can, V., Altun, U. & Okay, O. Nonionic double and triple network hydrogels of high mechanical strength. Macromolecules 47, 6430–6440 (2014).
Shams Es-haghi, S. & Weiss, R. A. Fabrication of tough hydrogels from chemically cross-linked multiple neutral networks. Macromolecules 49, 8980–8987 (2016).
Sun, T. L., Kurokawa, T., Kuroda, S., Ihsan, A. B., Akasaki, T., Sato, K., Haque, M. A., Nakajima, T. & Gong, J. P. Physical hydrogels composed of polyampholytes demonstrate high toughness and viscoelasticity. Nat. Mater. 12, 932–937 (2013).
Ihsan, A. B., Sun, T. L., Kuroda, S., Haque, M. A., Kurokawa, T., Nakajima, T. & Gong, J. P. A phase diagram of neutral polyampholyte—from solution to tough hydrogel. J. Mater. Chem. B 1, 4523–4702 (2013).
Luo, F., Sun, T. L., Nakajima, T., Kurokawa, T., Zhao, Y., Ihsan, A. B., Guo, H. L., Li, X. F. & Gong, J. P. Crack blunting and advancing behaviors of tough and self-healing polyampholyte hydrogel. Macromolecules 47, 6037–6046 (2014).
Ihsan, A. B., Sun, T. L., Kurokawa, T., Karobi, S. N., Nakajima, T., Nonoyama, T., Roy, C. K., Luo, F. & Gong, J. P. Self-healing behaviors of tough polyampholyte hydrogels. Macromolecules 49, 4245–4252 (2016).
Roy, C. K., Guo, H. L., Sun, T. L., Ihsan, A. B., Kurokawa, T., Takahata, M., Nonoyama, T., Nakajima, T. & Gong, J. P. Self-adjustable adhesion of polyampholyte hydrogels. Adv. Mater. 27, 7344–7348 (2015).
Luo, F., Sun, T. L., Nakajima, T., Kurokawa, T., Zhao, Y., Sato, K., Ihsan, A., Bin, Li, X., Guo, H. & Gong, J. P. Oppositely charged polyelectrolytes form tough, self-healing, and rebuildable hydrogels. Adv. Mater. 27, 2722–2727 (2015).
Luo, F., Sun, T. L., Nakajima, T., Kurokawa, T., Ihsan, A., Bin, Li, X., Guo, H. & Gong, J. P. Free reprocessability of tough and self-healing hydrogels based on polyion complex. ACS Macro Lett. 4, 1–6 (2015).
Sun, J.-Y., Zhao, X., Illeperuma, W. R. K., Chaudhuri, O., Oh, K. H., Mooney, D. J., Vlassak, J. J. & Suo, Z. Highly stretchable and tough hydrogels. Nature 489, 133–136 (2012).
Zhong, M., Liu, X.-Y., Shi, F., Zhang, L., Wang, X., Cheetham, A. G., Cui, H. & Xie, X.-M. Self-healable, tough and highly stretchable ionic nanocomposite physical hydrogels. Soft Matter 11, 4235–4241 (2015).
Haque, M. A., Kurokawa, T. & Gong, J. P. Anisotropic hydrogel based on bilayers: color, strength, toughness, and fatigue resistance. Soft Matter 8, 8008 (2012).
Haque, M. A., Kamita, G., Kurokawa, T., Tsujii, K. & Gong, J. P. Unidirectional alignment of lamellar bilayer in hydrogel: one-dimensional swelling, anisotropic modulus, and stress/strain tunable structural color. Adv. Mater. 22, 5110–5114 (2010).
Yue, Y., Kurokawa, T., Haque, M. A., Nakajima, T., Nonoyama, T., Li, X., Kajiwara, I. & Gong, J. P. Mechano-actuated ultrafast full-colour switching in layered photonic hydrogels. Nat. Commun 5, 4659 (2014).
Yue, Y. F., Haque, M. A., Kurokawa, T., Nakajima, T. & Gong, J. P. Lamellar hydrogels with high toughness and ternary tunable photonic stop-band. Adv. Mater. 25, 3106–3110 (2013).
Haque, M. A., Kurokawa, T., Kamita, G. & Gong, J. P. Lamellar bilayers as reversible sacrificial bonds to toughen hydrogel: hysteresis, self-recovery, fatigue resistance, and crack blunting. Macromolecules 44, 8916–8924 (2011).
Sato, K., Nakajima, T., Hisamatsu, T., Nonoyama, T., Kurokawa, T. & Gong, J. P. Phase-separation-induced anomalous stiffening, toughening, and self-healing of polyacrylamide gels. Adv. Mater. 27, 6990–6998 (2015).
Tuncaboylu, D. C., Sari, M., Oppermann, W. & Okay, O. Tough and self-healing hydrogels formed via hydrophobic interactions. Macromolecules 44, 4997–5005 (2011).
Kondo, S., Hiroi, T., Han, Y. S., Kim, T. H., Shibayama, M., Chung, U. Il & Sakai, T. Reliable hydrogel with mechanical ‘Fuse Link’ in an aqueous environment. Adv. Mater. 27, 7407–7411 (2015).
Guo, H., Sanson, N., Hourdet, D. & Marcellan, A. Thermoresponsive toughening with crack bifurcation in phase-separated hydrogels under isochoric conditions. Adv. Mater. 28, 5857–5864 (2016).
Smith, B. L., Schaffer, T. E., Viani, M., Thompson, J. B., Frederick, N. A., Kindt, J., Belcher, A. M., Stucky, G. D., Morse, D. E. & Hansma, P. K. Molecular mechanistic origin of the toughness of natural adhesives, fibres and composites. Nature 399, 761–763 (1999).
Thompson, J. B., Kindt, J. H., Drake, B., Hansma, H. G., Morse, D. E. & Hansma, P. K. Bone indentation recovery time correlates with bond reforming time. Nature 414, 773–776 (2001).
Yang, C. H., Chen, B., Lu, J. J., Yang, J. H., Zhou, J., Chen, Y. M. & Suo, Z. Ionic cable. Extrem. Mech. Lett. 3, 59–65 (2015).
Moghadam, F., Kamio, E., Yoshizumi, A. & Matsuyama, H. An amino acid ionic liquid-based tough ion gel membrane for CO2 capture. Chem. Commun. 51, 13658–13661 (2015).
Murosaki, T., Ahmed, N. & Gong, J. P. Antifouling properties of hydrogels. Sci. Technol. Adv. Mater. 12, 64706 (2011).
Acknowledgements
This work was partially supported by JSPS KAKENHI, grant numbers JP24225006, JP18002002 and JP26870008. This research was also partially funded by the ImPACT Program of the Council for Science, Technology and Innovation (Cabinet Office, Government of Japan). I thank Prof. Jian Ping Gong (Hokkaido University) and other co-workers for their great contribution to this research.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The authors declare no conflict of interest.
Rights and permissions
About this article
Cite this article
Nakajima, T. Generalization of the sacrificial bond principle for gel and elastomer toughening. Polym J 49, 477–485 (2017). https://doi.org/10.1038/pj.2017.12
Received:
Revised:
Accepted:
Published:
Issue date:
DOI: https://doi.org/10.1038/pj.2017.12
This article is cited by
-
Double-network hydrogels with a gradient hydrophobic coating that prevents water evaporation and allows strong adhesion to a solid substrate
Polymer Journal (2025)
-
Benzoxazines containing amide bonds and the toughening effect of amide bonds on polybenzoxazine
Polymer Bulletin (2025)
-
Engineering Smart Composite Hydrogels for Wearable Disease Monitoring
Nano-Micro Letters (2023)
-
A Microstructural Damage Model toward Simulating the Mullins Effect in Double-Network Hydrogels
Acta Mechanica Solida Sinica (2022)
-
Rheological studies on polymer networks with static and dynamic crosslinks
Polymer Journal (2021)
