Delayed recovery in a dense suspension of core-shell attractive particles

TL;DR

This study investigates the delayed recovery behavior of dense suspensions of core-shell attractive particles, revealing a power-law relaxation, a time-connectivity superposition, and a ductile-to-brittle transition linked to evolving particle interactions.

Contribution

It introduces a novel understanding of delayed recovery in soft glasses through a time-dependent interaction potential involving polymer shell deformation.

Findings

Power-law viscoelastic spectra upon flow cessation

Master curve indicating a time-connectivity superposition

Ductile-to-brittle transition with aging

Abstract

Soft particulate glasses are dense suspensions of jammed particles that flow like liquids under external shear and recover their solid-like properties almost instantly upon flow cessation. Here, we consider a dense suspension of core-shell attractive particles whose polymer brush allows for a delayed recovery that we monitor by time-resolved mechanical spectroscopy. Viscoelastic spectra recorded upon flow cessation show a striking power-law behavior and can be rescaled onto a master curve that hints at a time-connectivity superposition principle. Additionally, the non-linear response of this soft glass, measured at various aging times, shows a ductile-to-brittle transition, which suggests that the interactions between the particles display a progressive repulsive-to-attractive transition. These results depict an original scenario for the delayed recovery involving a time-dependent interaction potential in which attractive hydrophobic forces are only activated when neighboring particles deform their polymer shell and come in close contact.