Revisiting the strain-induced softening behaviour in hydrogels

Fuente: arXiv
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Main Authors: Duarte, L. K. R., Rizzi, L. G.
Format: Preprint
Published: 2024
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author Duarte, L. K. R.
Rizzi, L. G.
author_facet Duarte, L. K. R.
Rizzi, L. G.
contents Usually, the strain-induced softening behaviour observed in the differential modulus $K(T,γ)$ of hydrogels has been attributed to the breakage of internal structures of the network, such as the cross-links that bind together the polymer chains. Here we consider a stress-strain relationship that we have recently derived from a coarse-grained model to demonstrate that no rupture of the network is needed for rubber-like gels to present such behaviour. In particular, we show that, in some cases, the decreasing of $K(T,γ)$ as a function of the strain $γ$ is closely related to the energy-related contribution to the elastic modulus that has been experimentally observed, e.g., for tetra-PEG hydrogels. Thus, our results suggest that, instead of the breakage of structures, the softening behaviour can be also related to the effective interaction between the chains in the network and their neighbouring solvent molecules. Comparison to experimental data determined for several hydrogels is included to illustrate that behaviour and to validate our approach.
format Preprint
id arxiv_https___arxiv_org_abs_2405_18185
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Revisiting the strain-induced softening behaviour in hydrogels
Duarte, L. K. R.
Rizzi, L. G.
Soft Condensed Matter
Biological Physics
Chemical Physics
Computational Physics
Medical Physics
Usually, the strain-induced softening behaviour observed in the differential modulus $K(T,γ)$ of hydrogels has been attributed to the breakage of internal structures of the network, such as the cross-links that bind together the polymer chains. Here we consider a stress-strain relationship that we have recently derived from a coarse-grained model to demonstrate that no rupture of the network is needed for rubber-like gels to present such behaviour. In particular, we show that, in some cases, the decreasing of $K(T,γ)$ as a function of the strain $γ$ is closely related to the energy-related contribution to the elastic modulus that has been experimentally observed, e.g., for tetra-PEG hydrogels. Thus, our results suggest that, instead of the breakage of structures, the softening behaviour can be also related to the effective interaction between the chains in the network and their neighbouring solvent molecules. Comparison to experimental data determined for several hydrogels is included to illustrate that behaviour and to validate our approach.
title Revisiting the strain-induced softening behaviour in hydrogels
topic Soft Condensed Matter
Biological Physics
Chemical Physics
Computational Physics
Medical Physics
url https://arxiv.org/abs/2405.18185