Rate-Dependent Stiffness and Recovery in Interpenetrating Network Hydrogels through Sacrificial Metal Coordination Bonds.
Four-arm poly(ethylene glycol) (PEG) star polymers modified with 3-hydroxy-4-pyridinone (HOPO) end groups were shown to form transient, coordination networks upon addition of trivalent cations In3+, Fe3+, and Al3+. These coordination-based hydrogels exhibited high activation energies of viscoelasticity (34 kT) and characteristic bond lifetimes tunable over 2 orders of magnitude and could be incorporated into poly(hydroxyethylacrylamide)-based covalent scaffolds to create interpenetrating network hydrogels. Measurements carried out in compression and tension demonstrate that the secondary coordination network imparts toughness and stiffness to the overall material, and unlike traditional interpenetrating networks (IPNs), the extent of toughening is dependent on the rate at which the materials are deformed. The dynamic character of the coordination network also allows recovery after mechanical damage following high amplitude strains.
Graduate Program in Biomolecular Science and Engineering, University of California, Santa Barbara, California 93106, United States.
Matthew S
MS
Menyo
Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.
Craig J
CJ
Hawker
Graduate Program in Biomolecular Science and Engineering, University of California, Santa Barbara, California 93106, United States; Marine Science Institute, University of California, Santa Barbara, California 93106, United States.
J Herbert
JH
Waite