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Bond Reformation, Self-Recovery, and Toughness in Hydrogen-Bonded Hydrogels

Journal Article


Abstract


  • Tough hydrogels have gained attention due to their potential applications in biomimetics and soft robotics. Among all proposed topologies, tough hydrogels comprising physical bonds (e.g., hydrogen bonds) are of particular interest because of the possibility of bond reformation and subsequent rapid recovery of the network damage responsible for energy dissipation during loading. We developed a model based on a sequential debonding and time-dependent reformation of physical bonds to explain the unexpectedly high toughness of hydrogels formed by single networks of hydrogen-bonded hydrogels. First, a series of mechanical testing experiments were performed on various polyether-based hydrophilic polyurethanes with different numbers of proton acceptor and donor sites to evaluate the correlation between toughness and mechanical recovery with physical cross-linking. Then, the parameters of the model were obtained using the experimental results from load-unload tensile cycles with different resting times between cycles to provide an estimate of the bond dissociation and bond reformation rates. Finally, the measured fractured energies were successfully and quantitatively predicted by our model. This model can be further adapted to describe and predict the toughness of other physically cross-linked polymer networks, linking their structural parameters (i.e., level of physical cross-linking, chain length, and rate of bond reformation) with their mechanical properties and load recovery.

Publication Date


  • 2020

Citation


  • Oveissi, F., Spinks, G. M., & Naficy, S. (2020). Bond Reformation, Self-Recovery, and Toughness in Hydrogen-Bonded Hydrogels. ACS Applied Polymer Materials, 2(12), 5798-5807. doi:10.1021/acsapm.0c01009

Scopus Eid


  • 2-s2.0-85097884965

Start Page


  • 5798

End Page


  • 5807

Volume


  • 2

Issue


  • 12

Abstract


  • Tough hydrogels have gained attention due to their potential applications in biomimetics and soft robotics. Among all proposed topologies, tough hydrogels comprising physical bonds (e.g., hydrogen bonds) are of particular interest because of the possibility of bond reformation and subsequent rapid recovery of the network damage responsible for energy dissipation during loading. We developed a model based on a sequential debonding and time-dependent reformation of physical bonds to explain the unexpectedly high toughness of hydrogels formed by single networks of hydrogen-bonded hydrogels. First, a series of mechanical testing experiments were performed on various polyether-based hydrophilic polyurethanes with different numbers of proton acceptor and donor sites to evaluate the correlation between toughness and mechanical recovery with physical cross-linking. Then, the parameters of the model were obtained using the experimental results from load-unload tensile cycles with different resting times between cycles to provide an estimate of the bond dissociation and bond reformation rates. Finally, the measured fractured energies were successfully and quantitatively predicted by our model. This model can be further adapted to describe and predict the toughness of other physically cross-linked polymer networks, linking their structural parameters (i.e., level of physical cross-linking, chain length, and rate of bond reformation) with their mechanical properties and load recovery.

Publication Date


  • 2020

Citation


  • Oveissi, F., Spinks, G. M., & Naficy, S. (2020). Bond Reformation, Self-Recovery, and Toughness in Hydrogen-Bonded Hydrogels. ACS Applied Polymer Materials, 2(12), 5798-5807. doi:10.1021/acsapm.0c01009

Scopus Eid


  • 2-s2.0-85097884965

Start Page


  • 5798

End Page


  • 5807

Volume


  • 2

Issue


  • 12