Engineering mechanical dissipation in solid poly(ethylene glycol) hydrogels with bio-inspired metal-coordinate crosslinks
Author(s)Learsch, Robert (Robert Whitson)
Massachusetts Institute of Technology. Department of Materials Science and Engineering.
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Growing evidence supports that the unique mechanical behavior of mussel byssal threads, such as high toughness and self-healing, rely on an intricate balance of permanent covalent and reversible metal coordination bonds. Inspired by this material crosslink chemistry balance, we synthesized polyethylene glycol (PEG) hydrogels with two crosslinked networks; a primary permanent network composed of covalently crosslinked 4-arm PEG and a secondary network composed of 4-arm PEG functionalized with histidine on each arm. The histidine decorated PEG forms a mechanically reversible network via metal ion coordinated crosslinks. Using rheometry, we study the contribution of the metal-coordinate network to the bulk gels mechanics and find that we can control both the amplitude and the frequency of peak mechanical dissipation with the histidine: metal ion ratio and the choice of metal ion, respectively. Furthermore, we can control the mechanical contribution of metal coordinate bonds by changes in pH. These simple bio-inspired gels promise to serve as a new model system for further study of opto-mechanical coupling of metal-coordinate soft materials.
Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (page 32).
DepartmentMassachusetts Institute of Technology. Department of Materials Science and Engineering.
Massachusetts Institute of Technology
Materials Science and Engineering.