Giovanni Del Monte^1,2, Emanuela Zaccarelli^1*

1 CNR-ISC and Department of Physics, Sapienza University of Rome, p.le A. Moro 2, 00185 Roma, Italy

2 Soft Condensed Matter and Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, Netherlands

* Corresponding authors emails: emanuela.zaccarelli@cnr.it

DOI10.24435/materialscloud:4t-rb [version v1]

Publication date: Jan 24, 2025

How to cite this record

Giovanni Del Monte, Emanuela Zaccarelli, Numerical study of neutral and charged microgel suspensions: from single-particle to collective behavior, Materials Cloud Archive 2025.19 (2025), https://doi.org/10.24435/materialscloud:4t-rb

Description

We perform extensive molecular dynamics simulations of an ensemble of realistic microgel particles in swollen conditions in a wide range of packing fractions ζ. We compare neutral and charged microgels, where we consider charge distribution adherent to experimental conditions. Through a detailed analysis of singleparticle behavior, we are able to identify the different regimes occurring upon increasing concentration: from shrinking to deformation and interpenetration, always connecting our findings with available experimental observations. We then link these single-particle features with the collective behavior of the suspension, finding evidence of a structural reentrance that has no counterpart in the dynamics. Hence, while the maximum of the radial distribution function displays a nonmonotonic behavior with increasing ζ, the dynamics, quantified by the microgels’ mean-squared displacement, always slows down. This behavior, at odds with the simple Hertzian model, can be described by a phenomenological multi-Hertzian model, which takes into account the enhanced internal stiffness of the core. However, also this model fails when deformation enters into play, whereby more realistic many-body models are required. Thanks to our analysis, we are able to unveil the key physical mechanisms, shrinking and deformation, giving rise to the structural reentrance that holds up to very large packing fractions. We further identify key similarities and differences between neutral and charged microgels, for which we detect at high enough ζ the fusion of charged shells, previously invoked to explain key experimental findings, and responsible for the structural reentrance. Overall, our study establishes a powerful framework to uncover the physics of microgel suspensions, paving the way to tackle different regimes, e.g., high temperature, and internal architectures, such as for hollow and ultralow-cross-linked microgels, where experimental evidence is still limited.

Materials Cloud sections using this data

Files

File name	Size	Description
RAWdata.zip MD5md5:aef6669d95503b2609f399a1fe41ec27	58.7 MiB	Data presented in the article entitled "Numerical Study of Neutral and Charged Microgel Suspensions: From Single-Particle to Collective Behavior"

License

Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.
Metadata, except for email addresses, are licensed under the Creative Commons Attribution Share-Alike 4.0 International license.

External references

Keywords

microgels collective behavior elasticity