Journal Article

Deswelling and deformation of microgels in concentrated packings

van de Laar, T, Laboratoire de Génie Chimique (LGC) ; Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT), Physical chemistry and Soft matter group ; Wageningen University and Research [Wageningen] (WUR), Schroën, Karin, Laboratory of Food Process Engineering ; Wageningen University and Research [Wageningen] (WUR), Bouchoux, Antoine, Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP) ; Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse) ; Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Bouhid de Aguiar, Izabella, Meireles, Martine, European Commission-Education, Audio

2017

Overview

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.

• Publisher: Nature Publishing Group,CCSD,Nature Publishing Group UK
• Subject: 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
• ISBN: 0004087812000