A transient network of telechelic polymers and microspheres : structure and rheology

TL;DR

This paper investigates the structure and rheological behavior of a transient network formed by microemulsion droplets connected with telechelic polymers, revealing complex relaxation dynamics and fracture-like flow singularities.

Contribution

It provides a detailed analysis of the linear and nonlinear viscoelastic properties of the transient network, highlighting the role of elastic reorganizations and fracture behavior.

Findings

Stretched exponential stress relaxation in the linear regime

Fast and slow relaxation dynamics in the nonlinear regime

Flow curve singularity indicative of fracture behavior

Abstract

We study the structure and dynamics of a transient network composed of droplets of microemulsion connected by telechelic polymers. The polymer induces a bridging attraction between droplets without changing their shape. A viscoelastic behaviour is induced in the initially liquid solution, characterised in the linear regime by a stretched exponential stress relaxation. We analyse this relaxation in the light of classical theories of transient networks. The role of the elastic reorganisations in the deformed network is emphasized. In the non linear regime, a fast relaxation dynamics is followed by a second one having the same rate as in the linear regime. This behaviour, under step strain experiments, should induce a non monotonic behaviour in the elastic component of the stress under constant shear rate. However, we obtain in this case a singularity in the flow curve very different from the one observed in other systems, that we interpret in terms of fracture behaviour.