Soft ULC Microgels at the Interface Interact and Flow as Hertzian-Like Colloids

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Autori principali: Ruiz-Franco, José, Höfken, Tom, Schmidt, Maximilian M., Bochenek, Steffen, Zaccarelli, Emanuela, Scotti, Andrea
Natura: Preprint
Pubblicazione: 2025
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author Ruiz-Franco, José
Höfken, Tom
Schmidt, Maximilian M.
Bochenek, Steffen
Zaccarelli, Emanuela
Scotti, Andrea
author_facet Ruiz-Franco, José
Höfken, Tom
Schmidt, Maximilian M.
Bochenek, Steffen
Zaccarelli, Emanuela
Scotti, Andrea
contents Soft pair potentials predict a reentrant liquid phase for high concentrations, a behavior not observed experimentally. Here, very soft microgels confined at an oil-water interface are used as a model system of particles interacting via a soft potential in 2D. Interfacial rheology measurements demonstrate the existence of different flow regimes that depend on the compression of the monolayer. Such a compression also leads to a non-monotonic variation of the elastic moduli and of the yield stress of the monolayer. These results, together with the equilibrium phase behavior of the monolayer, are reproduced in molecular dynamics simulations of a 2D system of particles interacting with a Hertzian-like potential. Remarkably, due to the non-monotonic variation of the elastic moduli, we observe \textit{isoelastic} points where the monolayer shows the same stiffness at very different concentrations. These points are the experimental manifestation of the predicted reentrant liquid phase.
format Preprint
id arxiv_https___arxiv_org_abs_2501_09472
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Soft ULC Microgels at the Interface Interact and Flow as Hertzian-Like Colloids
Ruiz-Franco, José
Höfken, Tom
Schmidt, Maximilian M.
Bochenek, Steffen
Zaccarelli, Emanuela
Scotti, Andrea
Soft Condensed Matter
Soft pair potentials predict a reentrant liquid phase for high concentrations, a behavior not observed experimentally. Here, very soft microgels confined at an oil-water interface are used as a model system of particles interacting via a soft potential in 2D. Interfacial rheology measurements demonstrate the existence of different flow regimes that depend on the compression of the monolayer. Such a compression also leads to a non-monotonic variation of the elastic moduli and of the yield stress of the monolayer. These results, together with the equilibrium phase behavior of the monolayer, are reproduced in molecular dynamics simulations of a 2D system of particles interacting with a Hertzian-like potential. Remarkably, due to the non-monotonic variation of the elastic moduli, we observe \textit{isoelastic} points where the monolayer shows the same stiffness at very different concentrations. These points are the experimental manifestation of the predicted reentrant liquid phase.
title Soft ULC Microgels at the Interface Interact and Flow as Hertzian-Like Colloids
topic Soft Condensed Matter
url https://arxiv.org/abs/2501.09472