Paper Number
PO44 

Session
Poster Session

Title
Probing plastic rearrangements in colloidal gels during creep

Presentation Date and Time
October 13, 2021 (Wednesday) 6:30

Track / Room
Poster Session / Ballroom 1-2-3-4

Authors (Click on name to view author profile)

  1. Lehéricey, Pierre (ETH Zürich, Department of Materials)
  2. Stricker, Laura (ETH Zürich, Department of Materials)
  3. Isa, Lucio (ETH Zürich, Department of Materials)
  4. Vermant, Jan (ETH Zurich, Materials Departement)

Author and Affiliation Lines (in printed abstract book)
Pierre Lehéricey, Laura Stricker, Lucio Isa and Jan Vermant
Department of Materials, ETH Zürich, Zürich, Zürich 8093, Switzerland

Speaker / Presenter 
Lehéricey, Pierre

Keywords
experimental methods; colloids; gels

Text of Abstract
A mechanistic understanding of yielding of colloidal gels is of both fundamental and practical interest, especially in view of the widespread use of these materials. The emergence of a yield stress is attributed to the formation of a percolated colloidal network. Only a few rheo-confocal studies focused on the microstructural evolution during yielding1. However, due to their limited spatio-temporal resolution, these studies could, as yet, not provide a complete image of yielding at the colloidal network level.
Using a homemade ultrafast rheo-confocal setup2, we investigate the microstructure of a colloidal gel under constant shear scanning a 35 µm x 35 µm x 20 µm 3D voxel stack each second. Inspired by how structural rearrangements of particles trigger the yielding of colloidal glasses, we focus on the plastic rearrangements of particles of PMMA-g-PHSA in a model depletion gel under shear below or near the yield stress yielding. Image processing methods and particle tracking can be used to determine the local strain field stemming from plastic events and their propogation. We study the influence of the volume fraction and the depletion strength on such basic plastic events. We focus on the rearrangements before yielding, inspired by rheo-DLS experiments as precursors of yielding3, in order to assess their impact on the subsequent macroscopic yielding.

1 : B. Rajaram et A. Mohraz, Soft Matter, 2010, 6
2 : G. Colombo et al., Korea-Australia Rheology Journal, 2019, 31
3 : S. Aime et al., PNAS, 2018, 115