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Updated: May 18, 2026

Controlled Strain of 3D Hydrogels under Live Microscopy Imaging
Published on: December 4, 2020
Role of isostaticity and load-bearing microstructure in the elasticity of yielded colloidal gels
Lilian C Hsiao1, Richmond S Newman, Sharon C Glotzer
1Department of Chemical Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, MI 48109, USA.
Abstract:
We report a simple correlation between microstructure and strain-dependent elasticity in colloidal gels by visualizing the evolution of cluster structure in high strain-rate flows. We control the initial gel microstructure by inducing different levels of isotropic depletion attraction between particles suspended in refractive index matched solvents. Contrary to previous ideas from mode coupling and micromechanical treatments, our studies show that bond breakage occurs mainly due to the erosion of rigid clusters that persist far beyond the yield strain. This rigidity contributes to gel elasticity even when the sample is fully fluidized; the origin of the elasticity is the slow Brownian relaxation of rigid, hydrodynamically interacting clusters. We find a power-law scaling of the elastic modulus with the stress-bearing volume fraction that is valid over a range of volume fractions and gelation conditions. These results provide a conceptual framework to quantitatively connect the flow-induced microstructure of soft materials to their nonlinear rheology.
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