Interpenetration of polymeric microgels at ultrahigh densities

Abstract Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a s can be smaller than the initial unperturbed particle diameter σ 0, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels...

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Main Authors: Priti S. Mohanty, Sofi Nöjd, Kitty van Gruijthuijsen, Jérôme J. Crassous, Marc Obiols-Rabasa, Ralf Schweins, Anna Stradner, Peter Schurtenberger
Format: Article
Language:English
Published: Nature Portfolio 2017-05-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-017-01471-3
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author Priti S. Mohanty
Sofi Nöjd
Kitty van Gruijthuijsen
Jérôme J. Crassous
Marc Obiols-Rabasa
Ralf Schweins
Anna Stradner
Peter Schurtenberger
author_facet Priti S. Mohanty
Sofi Nöjd
Kitty van Gruijthuijsen
Jérôme J. Crassous
Marc Obiols-Rabasa
Ralf Schweins
Anna Stradner
Peter Schurtenberger
author_sort Priti S. Mohanty
collection DOAJ
description Abstract Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a s can be smaller than the initial unperturbed particle diameter σ 0, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels at ultrahigh densities, we know surprisingly little about their response to their environment at effective volume fractions ϕ eff above close packing (ϕ cp ), and the existing information is often contradictory. Here we report direct measurements of the size and shape of poly(N-isopropylacrylamide) microgels at concentrations below and above ϕ cp using the zero average contrast method in small-angle neutron scattering. We complement these experiments with measurements of the average interparticle distances using small-angle x-ray scattering, and a determination of the glass transition using dynamic light scattering. This allows us to unambiguously decouple interaction effects from density-dependent variations of the particle size and shape at all values of ϕ eff . We demonstrate that the microgels used in this study significantly interpenetrate and thus change their size and shape only marginally even for ϕ eff  ≫ ϕ cp , a finding that may require changes in the interpretation of a number of previously published studies on the structural and dynamic properties of dense soft particle systems.
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spelling doaj.art-e40e0616ef2447a9909ee1d294f3d7d92022-12-21T22:56:08ZengNature PortfolioScientific Reports2045-23222017-05-017111210.1038/s41598-017-01471-3Interpenetration of polymeric microgels at ultrahigh densitiesPriti S. Mohanty0Sofi Nöjd1Kitty van Gruijthuijsen2Jérôme J. Crassous3Marc Obiols-Rabasa4Ralf Schweins5Anna Stradner6Peter Schurtenberger7Physical Chemistry, Department of Chemistry, Lund UniversityPhysical Chemistry, Department of Chemistry, Lund UniversityAdolphe Merkle Institute, University of FribourgPhysical Chemistry, Department of Chemistry, Lund UniversityPhysical Chemistry, Department of Chemistry, Lund UniversityLarge Scale Structures Group, Institut Laue-LangevinPhysical Chemistry, Department of Chemistry, Lund UniversityPhysical Chemistry, Department of Chemistry, Lund UniversityAbstract Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a s can be smaller than the initial unperturbed particle diameter σ 0, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels at ultrahigh densities, we know surprisingly little about their response to their environment at effective volume fractions ϕ eff above close packing (ϕ cp ), and the existing information is often contradictory. Here we report direct measurements of the size and shape of poly(N-isopropylacrylamide) microgels at concentrations below and above ϕ cp using the zero average contrast method in small-angle neutron scattering. We complement these experiments with measurements of the average interparticle distances using small-angle x-ray scattering, and a determination of the glass transition using dynamic light scattering. This allows us to unambiguously decouple interaction effects from density-dependent variations of the particle size and shape at all values of ϕ eff . We demonstrate that the microgels used in this study significantly interpenetrate and thus change their size and shape only marginally even for ϕ eff  ≫ ϕ cp , a finding that may require changes in the interpretation of a number of previously published studies on the structural and dynamic properties of dense soft particle systems.https://doi.org/10.1038/s41598-017-01471-3
spellingShingle Priti S. Mohanty
Sofi Nöjd
Kitty van Gruijthuijsen
Jérôme J. Crassous
Marc Obiols-Rabasa
Ralf Schweins
Anna Stradner
Peter Schurtenberger
Interpenetration of polymeric microgels at ultrahigh densities
Scientific Reports
title Interpenetration of polymeric microgels at ultrahigh densities
title_full Interpenetration of polymeric microgels at ultrahigh densities
title_fullStr Interpenetration of polymeric microgels at ultrahigh densities
title_full_unstemmed Interpenetration of polymeric microgels at ultrahigh densities
title_short Interpenetration of polymeric microgels at ultrahigh densities
title_sort interpenetration of polymeric microgels at ultrahigh densities
url https://doi.org/10.1038/s41598-017-01471-3
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