Viscosity of macromolecules with complex architecture

TL;DR

This study uses non-equilibrium molecular dynamics simulations to analyze how the complex architecture of microgels influences their viscosity and shear thinning behavior, highlighting the impact of cross-linking density and particle shape.

Contribution

It provides a systematic computational analysis of microgel rheology, comparing it to simpler polymer systems and revealing the effects of topology and cross-linking on viscosity.

Findings

Microgel cross-linking density significantly affects viscosity.

Microgel dispersions exhibit less shear thinning than simpler polymers.

Particle shape influences the rheological properties of microgels.

Abstract

It is well-known that the architecture of macromolecules plays an important role in the hydrodynamics and viscosity of its semi-diluted solutions. However, the systematic study of the rheology of macromolecules with complex topology, such as microgels, remains a difficult task. In this work, we use the computer simulations methods of non-equilibrium molecular dynamics to study the viscous properties of randomly cross-linked microgels and compare it to multiple reference systems (linear chains, 10-arm star polymers and hard spheres). We show that the microgel cross-linking density and, thus, the particle shape, plays crucial role in its viscosity. Also, in contrast to a simpler polymer systems, microgel dispersions in good solvent show much less shear thinning.