Deswelling and deformation of microgels in concentrated packings

Increasing the particle density of a suspension of microgel colloids above the point of random-close packing, must involve deformations of the particle to accommodate the increase in volume fraction. By contrast to the isotropic osmotic deswelling of soft particles, the particle-particle contacts gi...

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Bibliographic Details
Published in:	Scientific reports Vol. 7; no. 1; p. 10223
Main Authors:	Bouhid de Aguiar, I., van de Laar, T., Meireles, M., Bouchoux, A., Sprakel, J., Schroën, K.
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 31-08-2017 Nature Publishing Group
Subjects:	639/301/923/1027 639/301/923/218 Biotechnology Chemical and Process Engineering Colloids Deformation Engineering Sciences Experiments Food Process Engineering Humanities and Social Sciences Leerstoelgroep Levensmiddelenproceskunde Levensmiddelenproceskunde Life Sciences Mechanics Microscopy multidisciplinary Packing Physical Chemistry and Soft Matter Science Science (multidisciplinary) VLAG
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Summary:	Increasing the particle density of a suspension of microgel colloids above the point of random-close packing, must involve deformations of the particle to accommodate the increase in volume fraction. By contrast to the isotropic osmotic deswelling of soft particles, the particle-particle contacts give rise to a non-homogeneous pressure, raising the question if these deformations occur through homogeneous deswelling or by the formation of facets. Here we aim to answer this question through a combination of imaging of individual microgels in dense packings and a simple model to describe the balance between shape versus volume changes. We find a transition from shape changes at low pressures to volume changes at high pressures, which can be explained qualitatively with our model. Whereas contact mechanics govern at low pressures giving rise to facets, osmotic effects govern at higher pressures, which leads to a more homogeneous deswelling. Our results show that both types of deformation play a large role in highly concentrated microgel suspensions and thus must be taken into account to arrive at an accurate description of the structure, dynamics and mechanics of concentrated suspensions of soft spheres.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	2045-2322 2045-2322
DOI:	10.1038/s41598-017-10788-y