Structural Signature of a Brittle-to-Ductile Transition in Self-Assembled Networks

TL;DR

This study investigates the nonlinear rheology of surfactant micelle networks linked by block copolymers, revealing a brittle-to-ductile transition correlated with micelle morphology changes through combined rheology and structural analysis.

Contribution

It introduces a novel method coupling rheology with structural measurements to identify fracture processes and characterize the brittle-to-ductile transition in transient gels.

Findings

Signature of brittle-to-ductile transition observed

Micelle morphology influences fracture behavior

Fluctuations in micelle alignment serve as fracture probes

Abstract

We study the nonlinear rheology of a novel class of transient networks, made of surfactant micelles of tunable morphology reversibly linked by block copolymers. We couple rheology and time-resolved structural measurements, using synchrotron radiation, to characterize the highly nonlinear viscoelastic regime. We propose the fluctuations of the degree of alignment of the micelles under shear as a probe to identify a fracture process. We show a clear signature of a brittle-to-ductile transition in transient gels, as the morphology of the micelles varies, and provide a parallel between the fracture of solids and the fracture under shear of viscoelastic fluids.