# Tough hydrogels: sacrificial bonds that break so the gel does not

> A radial graphical abstract on tough hydrogels: a live 3D water-swollen polymer network at the hub, with four satellites on its structure, the sacrificial-bond mechanism, the numbers and the uses. Ordinary gels are brittle; double-network and ionic–covalent hybrid gels add weak bonds that break first and dissipate energy, lifting the fracture energy from about 10 to about 9,000 J m⁻².

- Page: https://www.labcanvas.com/templates/graphical-abstracts/tough-hydrogels-sacrificial-bonds-that-break-so-gel-does-not
- Open in the LabCanvas editor (LabCanvas account): https://www.labcanvas.com/editor.html?template=tough-hydrogels-sacrificial-bonds
- Updated: 2026-10-14
- Category: Materials graphical abstracts
- Method: Graphical abstract
- Starting materials: A water-swollen polymer network, about 90% water
- Product: A tough, highly stretchable hydrogel
- Key result: Alginate–polyacrylamide: about 90% water, stretch beyond 20 (17 with a notch), fracture energy about 9,000 J m⁻², against about 10 J m⁻² for most hydrogels (Sun et al., Nature 2012)
- Figure: 1920 × 1080 px, 89 editable layers (5 generated objects with settings)

## Steps

1. **Network structure**: Two interlaced networks: alginate held by Ca²⁺ ionic cross-links and polyacrylamide held by covalent cross-links, about 90% water
2. **Sacrificial bonds**: Under stretch the weak bonds (the brittle first network, or the ionic cross-links) break first and dissipate energy while the stretchy network bridges the crack; ionic cross-links can re-zip
3. **The numbers**: Fracture energy about 10 J m⁻² for most hydrogels, about 1,000 for double-network gels and cartilage, about 9,000 for alginate–polyacrylamide, which stretches beyond 20 times its length
4. **Uses**: Hydraulic soft actuators and robots, scaffolds and artificial soft tissues, tough adhesives for wet surfaces

## Uses

- Soft actuators and robots
- Tissue-engineering scaffolds and artificial cartilage
- Tough adhesives for wet tissue
- Teaching soft-matter toughening

## References

1. Sun et al., “Highly stretchable and tough hydrogels”, Nature 2012. https://doi.org/10.1038/nature11409 (primary)
2. Nonoyama & Gong, “Double-network hydrogel and its potential biomedical application: A review”, Proc. Inst. Mech. Eng. H 2015. https://doi.org/10.1177/0954411915606935 (review)
3. Nonoyama & Gong, “Tough Double Network Hydrogel and Its Biomedical Applications”, Annu. Rev. Chem. Biomol. Eng. 2021. https://doi.org/10.1146/annurev-chembioeng-101220-080338 (review)
4. Yuk et al., “Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water”, Nat. Commun. 2017. https://doi.org/10.1038/ncomms14230 (further reading)
5. Li et al., “Tough adhesives for diverse wet surfaces”, Science 2017. https://doi.org/10.1126/science.aah6362 (further reading)

Credit: Drawn by LabCanvas after Sun et al., Nature 2012 (doi:10.1038/nature11409); Nonoyama & Gong, Proc. Inst. Mech. Eng. H 2015 (doi:10.1177/0954411915606935); Yuk et al., Nat. Commun. 2017 (doi:10.1038/ncomms14230) and Li et al., Science 2017 (doi:10.1126/science.aah6362).

## Questions

**What does the “Tough hydrogels: sacrificial bonds that break so the gel does not” template show?** A radial graphical abstract on tough hydrogels: a live 3D water-swollen polymer network at the hub, with four satellites on its structure, the sacrificial-bond mechanism, the numbers and the uses. Ordinary gels are brittle; double-network and ionic–covalent hybrid gels add weak bonds that break first and dissipate energy, lifting the fracture energy from about 10 to about 9,000 J m⁻².

**What are the steps shown in “Tough hydrogels: sacrificial bonds that break so the gel does not”?** 1. Network structure: Two interlaced networks: alginate held by Ca²⁺ ionic cross-links and polyacrylamide held by covalent cross-links, about 90% water. 2. Sacrificial bonds: Under stretch the weak bonds (the brittle first network, or the ionic cross-links) break first and dissipate energy while the stretchy network bridges the crack; ionic cross-links can re-zip. 3. The numbers: Fracture energy about 10 J m⁻² for most hydrogels, about 1,000 for double-network gels and cartilage, about 9,000 for alginate–polyacrylamide, which stretches beyond 20 times its length. 4. Uses: Hydraulic soft actuators and robots, scaffolds and artificial soft tissues, tough adhesives for wet surfaces.

**What are the starting materials and the product?** Starting materials: A water-swollen polymer network, about 90% water. Product: A tough, highly stretchable hydrogel.

**Which papers is “Tough hydrogels: sacrificial bonds that break so the gel does not” based on?** Sun et al., “Highly stretchable and tough hydrogels”, Nature 2012 (doi:10.1038/nature11409); Nonoyama & Gong, “Double-network hydrogel and its potential biomedical application: A review”, Proc. Inst. Mech. Eng. H 2015 (doi:10.1177/0954411915606935); Nonoyama & Gong, “Tough Double Network Hydrogel and Its Biomedical Applications”, Annu. Rev. Chem. Biomol. Eng. 2021 (doi:10.1146/annurev-chembioeng-101220-080338); Yuk et al., “Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water”, Nat. Commun. 2017 (doi:10.1038/ncomms14230); Li et al., “Tough adhesives for diverse wet surfaces”, Science 2017 (doi:10.1126/science.aah6362).

**Can I edit the “Tough hydrogels: sacrificial bonds that break so the gel does not” template?** Yes. Open it in the LabCanvas editor: all 89 layers are editable, including 5 generated objects (structures, plots, equipment) with their own settings. Change the text, colours and layout, then export PNG, TIFF, SVG or PDF.

**Do I need an account to use this template?** Not to view it here. To open and edit it, sign in to LabCanvas or create a free account (the free plan keeps up to 3 designs). Downloading the figure is part of LabCanvas Pro (US$19 a month or US$199 a year).