Shear Thickening Behavior in Injectable Tetra-PEG Hydrogels Cross-Linked via Dynamic Thia-Michael Addition Bonds

08 August 2023, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


Injectable poly(ethylene glycol, PEG)-based hydrogels were reversibly crosslinked through thia-conjugate addition bonds and demonstrated to shear thicken at low shear rates. Crosslinking bond exchange kinetics and dilute polymer concentrations were leveraged to tune hydrogel plateau moduli (from 60 - 650 Pa) and relaxation times (2 - 8 seconds). Under continuous flow shear rheometry, these properties affected the onset of shear thickening and the degree of shear thickening achieved before a flow instability occurred. The changes in viscosity were reversible whether the shear rate increased or decreased, suggesting that chain stretching drives this behavior. Given the relevance of dynamic PEG hydrogels under shear to biomedical applications, their injectability was investigated, and injection forces were found to increase with higher polymer concentrations and slower bond exchange kinetics. Altogether, these results characterize the nonlinear rheology of dilute, dynamic covalent tetra-PEG hydrogels and offer insight to the mechanism driving their shear thickening behavior.


dynamic covalent
shear thickening

Supplementary materials

Supporting Information
Supporting Information includes 1H NMR spectra, oscillatory strain sweeps, fits to the Maxwell model, measurements of the shear stress as a function of time, shear stress sweeps, and estimates of crosslinking concentration.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.