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arXiv · 2407.20821

Hyper-Auxeticity and the Volume Phase Transition of Polymer Gels

Andrea Ninarello·Emanuela Zaccarelli
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Abstract

Thermoresponsive hydrogels exhibit reversible deswelling at the Volume Phase Transition (VPT), associated to a minimum of the Poisson's ratio $\nu$. Recent numerical investigations uncovered the occurrence of a Hyper-Auxetic Transition (HAT) ($\nu=-1$) for low-crosslinked hydrogels at low temperature, accompanied by a critical-like behavior. Here, we perform extensive numerical simulations to unveil the relation between these two transitions. We find that the HAT occurs at different temperatures $T$ up to a maximum value of the crosslinker concentration $c$, thus being clearly distinct from the VPT, taking place at fixed $T$ and for all $c$. Our results provide novel fundamental insights on the interplay between network collapse and mechanical properties of these fascinating materials.

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Andrea Ninarello, Emanuela Zaccarelli. 2024-07-30. Hyper-Auxeticity and the Volume Phase Transition of Polymer Gels. https://arxiv.org/abs/2407.20821

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