Fatigue and Fracture Resistant Hydrogels

Soft Tissue Replacement

At a Glance

​Researchers at Colorado State University have developed a hydrogel which retains its mechanical properties through multiple mechanical compression cycles while also being resistant to tears propagation. The fatigue resistance and fracture resistance in the hydrogel is accompanied by high modulus at low strains, elasticity, and a one second recovery of mechanical properties after compression.  The design of the polymer network uses the core-shell-sphere block copolymer morphology and hydrophobic interactions to maintain fatigue resistance in the hydrogel while also adding fracture resistance. The presence of both fatigue and fracture resistance is unique in hydrogel networks.


Clever integration of energy dissipating mechanisms into a range of unique network architectures has produced hydrogels with exceptional stretchability, ultimate strength, and overall toughness. Inclusion of secondary (interpenetrating) networks, hydrophobic aggregates, ionic interactions, deformable domain structures, and their various combinations has produced intriguing network designs aimed at pushing the boundaries of mechanical achievement.

Despite the considerable progress, most of the developed hydrogel systems are plagued by significant plastic deformation under cyclic loading, due to either permanent covalent bond rupture or (slow) bond reorganization precluding the network from returning to its original configuration.

Even in those few examples in which full recovery is possible, time scales for those processes are notoriously slow taking at best several minutes and in many cases hours or days. None of these examples would be acceptable as soft tissue replacement materials, for example, where recovery times on the order of a second or faster are prerequisite. Importantly, fatigue resistant dissipative systems in which recovery is rapid (~1s) and reproducible over thousands of cycles have yet to be demonstrated.


  • Both fracture resistant and fatigue resistant
  • Maintains mechanical properties over multiple cycles unlike double-network hydrogels
  • Sub second recovery times (others take hours or even days)


  • Soft tissue replacement
  • Co2 separation membranes (RTILs)
  • Battery separators
  • Materials for advanced impact protection
Last Updated: April 2022
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Travis Bailey
Allee Klug

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Steve Foster