Issue 25, 2018

Ideal reversible polymer networks


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.

Graphical abstract: Ideal reversible polymer networks

Article information

Article type
27 Mar 2018
10 May 2018
First published
15 May 2018
This article is Open Access
Creative Commons BY-NC license

Soft Matter, 2018,14, 5186-5196

Ideal reversible polymer networks

G. A. Parada and X. Zhao, Soft Matter, 2018, 14, 5186 DOI: 10.1039/C8SM00646F

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