Ideal reversible polymer networks
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c8sm00646f.pdf
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2.69 MB
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Adobe PDF
Checksum (MD5)
024bcb5ac684ba037c8c9e208c4b89ae
Author(s)
Parada Hernandez, German Alberto
Zhao, Xuanhe
Date Issued
May 2018
Journal
Soft Matter
Publisher
Royal Society of Chemistry
Citation
Parada, German Alberto, and Xuanhe Zhao. “Ideal Reversible Polymer Networks.” Soft Matter, vol. 14, no. 25, 2018, pp. 5186–96. © 2018 The Royal Society of Chemistry.
Version
Final published version
Abstract
In this article we introduce the concept of ideal reversible polymer networks, which have well-controlled polymer network structures similar to ideal covalent polymer networks but exhibit viscoelastic behaviors due to the presence of reversible crosslinks. We first present a theory to describe the mechanical properties of ideal reversible polymer networks. Because short polymer chains of equal length are used to construct the network, there are no chain entanglements and the chains' Rouse relaxation time is much shorter than the reversible crosslinks' characteristic time. Therefore, the ideal reversible polymer network behaves as a single Maxwell element of a spring and a dashpot in series, with the instantaneous shear modulus and relaxation time determined by the concentration of elastically-active chains and the dynamics of reversible crosslinks, respectively. The theory provides general methods to (i) independently control the instantaneous shear modulus and relaxation time of the networks, and to (ii) quantitatively measure kinetic parameters of the reversible crosslinks, including reaction rates and activation energies, from macroscopic viscoelastic measurements. To validate the proposed theory and methods, we synthesized and characterized the mechanical properties of a hydrogel composed of 4-arm polyethylene glycol (PEG) polymers end-functionalized with reversible crosslinks. All the experiments conducted by varying pH, temperature and polymer concentration were consistent with the predictions of our proposed theory and methods for ideal reversible polymer networks.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Creative Commons Attribution-NonCommercial 3.0 Unported
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DOI of Published Version
https://doi.org/10.1039/c8sm00646f
