Speaker: Luca Cipelletti
Affiliation: University of Montpellier FRANCE
Date: October 27th 3 PM
Where: Zoom and YouTube
Title: A unified state diagram for the yielding transition of soft colloids
Link INDICO https://indico.dfa.unipd.it/event/576/
Zoom Link https://unipd.link/ColloquiumDFA-27-10-2022
YouTube Link: https://unipd.link/AulaRostagniUniPadovaDFA
Abstract:
Concentrated colloidal suspensions and emulsions are a prototypical example of amorphous soft solids, widespread in technological and industrial applications and intensively studied as model systems in physics and material sciences. Soft solids are easily fluidized by applying a mechanical stress, thereby the undergo a so-called yielding transition. Although the yielding transition has been actively investigated, no consensus on a unified description has emerged so far. Here, we investigate yielding in three classes of soft solids, using analytical and numerical modelling and experiments probing simultaneously the microscopic dynamics and mechanical response under an imposed oscillatory shear deformation of variable amplitude. We find that at the microscopic level yielding consists in a transition, sharper than for rheological quantities, between two distinct dynamical states. We propose a lattice model with dynamical coupling between neighboring sites that captures the generic features of our experiments, leading to a unified state diagram for yielding. Disorder in the dynamical coupling plays a major role in the emergence of first-order-like vs second-order-like features in yielding, allowing for reconciling previous contrasting observations on the nature of the transition
S. Aime1 , D. Truzzolillo1 , D. J. Pine2 , L. Ramos1 , L. Cipelletti1,3
1 Laboratoire Charles Coulomb (L2C), Universit\'e Montpellier, CNRS, Montpellier, France
2 New York University
3 Institut Universitaire de France
Giampaolo Mistura
